Before the appearance of user-generated content (UGC), sharing personal travel experiences through social media applications was limited to a narrow circle of friends and family. For instance, if the tourist had a bad experience at the tourist destination, the image and reputation of the tourist destination would not be seriously damaged. The growth of Web 2.0 and social media has enabled the development of user-generated content and sharing comments, reviews and opinions on websites such as tripadvisor.com, facebook.com, youtube.com, instagram.com and twitter.com. Today, tourists are increasingly participating in information processes. When booking a trip, tourists (social media users) exchange opinions via modern media and shape the tourism destination reputation, thus affecting the travel decision. The advantage of user-generated content is reflected in data collected within a natural environment. Tourists share information, experiences and emotions about services, brands, tourism providers and destinations (Horster & Gottschalk, 2012). Thus, tourist reviews on social media can be considered a crucial source of information. The so-called online reputation of a tourism destination represents an open process where tourists share their reviews and opinions about tourist destinations through social media, which builds the destination image and tourist satisfaction and/or dissatisfaction, while tourism products or services have the ability to impact the tourists’ emotional state and decision to book and purchase tourist products and services (Chun, 2005). Based on the foregoing the question arises if it is possible, through deeper understanding and measuring, to determine the relationship between tourism destination reputation on social media and tourist satisfaction? The main objective of this doctoral thesis is: (a) to explore and extend the existing theoretical knowledge about tourism destination reputation on social media and tourist satisfaction, (b) to develop a conceptual model for measuring the relationship between tourism destination reputation on social media and tourist satisfaction, and (c) to examine the validity and reliability of the structural model. Specific objectives of this doctoral thesis are observed from the conceptual, empirical and applicative point of view. Based on the previous literature review, research results and research objectives, the main hypothesis was defined: based on the theoretical and empirical scientific knowledge about the concepts tourism destination reputation on social media and tourist satisfaction, and the proposed conceptual model, it is possible to determine the influence of the observed concepts using the partial least squares structural equation modeling method (PLS-SEM). In view of the proposed main hypothesis and conceptual model, the following auxiliary hypotheses are proposed: H1: There is a positive and significant relationship between message components on social media and tourism destination reputation on social media. H2: There is a positive and significant relationship between attitude towards comments on social media and tourism destination reputation on social media. H3: There is a positive and significant relationship between trust in social media and tourism destination reputation on social media. H4: There is a positive and significant relationship between tourism destination reputation on social media and tourist satisfaction. In order to test the proposed research hypotheses, empirical research was conducted, which is based on primary data using the survey method. The questionnaire was designed in English, Croatian, German and Italian language and contains 46 variables and the socio-demographic profile of the respondents. In order to test the relationship between the constructs and the proposed hypotheses, a structural model was developed. The developed model consists of three exogenous and two endogenous constructs and 23 formative and 23 reflective variables. The empirical research was conducted on the western coast of Istria (Croatia), from the beginning of July to the end of September 2016 and 2017. The respondents were tourists who were informed about the tourist destination on social media before traveling to the destination. The qualitative data analysis is based on 305 valid survey questionnaires. The primary data were analysed using univariate and multivariate statistical analysis, i.e. partial least squares structural equation modeling method (PLS-SEM). The analysis of the demographic profile of the respondents indicates that 57.4 per cent were male and 42.6 per cent female. Most of the respondents were between 31 and 40 years old and had a higher education. The sample includes respondents from 17 countries, while the largest number of respondents came from Germany, Italy and Austria. More than half of the respondents (62.3 per cent) were advanced or expert users of the Internet. When searching information online, 72.8 per cent use other tourists’ comments as an information source. Furthermore, 49.8 per cent of the respondents read consumer reviews on travel review portals (for example TripAdvisor), 46.2 per cent use social media as an information source (for example Facebook), 41.6 per cent use social sharing sites (for example YouTube, Flickr, Instagram), while 13.4 per cent of the respondents search for information on blogs and microblogs (for example Twitter, TravelPod). The most reliable sources are perceived as those which provide recent information (52.5 per cent) and those which have the most votes and likes (42.6 per cent). While asking the question “Can the content (comments, audio, video) produced by other tourists change your decision in choosing a destination?”, 46.6 per cent of the respondents answered “yes”, 41.6 per cent “no” and 11.8 per cent did not know. The results related to structural model testing confirmed three out of four auxiliary hypotheses. The strongest, positive and significant relationship between the latent constructs tourism destination reputation on social media and tourist satisfaction (0.590) is confirmed. A moderate, positive and significant relationship is observed between the latent constructs of message components on social media and tourism destination reputation on social media (0.469). A weak relationship is noticed between the latent construct attitude towards comments on social media and tourism destination reputation on social media (0.197), while the relationship between trust in social media and tourism destination reputation on social media almost does not exist (0.009) and is not significant. According to the indicators of validity, consistency, collinearity, significance and relevance of outer loadings, the structural model is considered as valid and reliable in measuring the relationship between tourism destination reputation on social media and tourist satisfaction, thus the main scientific hypothesis is confirmed. Although the doctoral thesis aimed to provide high quality, scientifically based theoretical, methodological and practical insights that can be used to accomplish some of the most important goals of tourism management, empirical research has several limitations to be taken into consideration when generalizing the results, which refer to: The choice of tourist destination – the empirical research was conducted on the western coast of Istria, also called Blue Istria. The eastern part and the countryside of Istria (Green Istria) was not covered by the research. The question remains whether the reputation of Blue and Green Istria on social media is different, and whether the results can be generalized at the destination level?  The data collection period - the research period covers the months of July, August and September 2016 and 2017, which may limit the empirical research. The data collection is restricted to tourists who stayed at the destination during the mentioned time period. Tourists staying in the destination outside the main season may or may not have different attitudes.  The sample of respondents – the sample includes only respondents who voluntarily participated in the research. Due to the specific target group, a convenient sample was used which lead to the conclusion that the data cannot be generalized and representative. Also, it should be considered that the sample population is relatively small in comparison to the entire population. It accounts for only 0.01 % of the total tourist arrivals in the west and south coast of Istria, although it meets the conditions for applying a complex multivariate statistical analysis.  Questionnaire design – the questionnaire design is based on previous research and consists of 46 variables and the socio-demographic characteristics of the respondents, which significantly burdens the respondents when completing the questionnaire, thus compromising the quality of the obtained data. Moreover, the questionnaires were obtained with the help of multiple interviewers, which influenced the socio-demographic profile of the respondents and the sample.  Measurement scale – although the ordinal Likert scale is a very popular psychometric scale that seeks to measure attitudes, interests, and perceptions, it is generally considered to violate some statistical assumptions needed to evaluate normally distributed data and parametric tests. This presents a problem because parametric statistics are generally considered more significant than nonparametric statistics. For this purpose (perhaps) it would be better to use visual analogue scales, interval scales or ration scales that can be equally effective and provide better data for parametric statistical analysis. The doctoral thesis contributes to the existing literature on the concepts of tourism destination reputation on social media and tourist satisfaction with regard to conceptual, methodological and applicative terms. In terms of the conceptual research, the doctoral thesis contributes to:  the development of scientific thought about the concept of tourism destination reputation on social media  the development of scientific thought about the concept of tourist satisfaction  the examination of the relationship between the concepts of tourism destination reputation on social media and tourist satisfaction  the presentation of existing methods and models for measuring the concept of tourism destination reputation on social media  the presentation of existing methods and models for measuring the concept of tourist satisfaction  the development of a conceptual model for measuring the relationship between tourism destination reputation on social media and tourist satisfaction. In terms of the methodological part of the scientific research, the contribution is reflected in:  determining the relationship of social media and tourism destination reputation  determining the tourism destination reputation based on the statements of the selected tourist segments  defining a model for determining the relationship between tourism destination reputation on social media and tourist satisfaction  applying the multivariate statistical analysis method in measuring the relationship between the concepts of tourism destination reputation on social media and tourist satisfaction  testing the reliability and validity of the research instrument  comparing the existing model for measuring the online reputation of a tourist destination (Marchiori et al., 2013), with the aim of testing the significance of nonparametric and parametric statistical analysis methods  comparing the results of previous research of domestic and foreign authors. In terms of the applicative part of the doctoral thesis, the scientific contribution is reflected in:  the confirmation of significance of selected model research concepts through the structural model presentation and results to destination management and stakeholders  specific recommendations for destination management. According to the PhD candidate’s best knowledge, this doctoral thesis is the first research and measurement of the relationship between tourism destination reputation on social media and tourist satisfaction in Croatia. Moreover, a similar research has not been published in international literature. In conclusion, the proposed conceptual model provides a valid and reliable basis for future research and for the continuous monitoring and improving of the tourism destination reputation on social media and tourist satisfaction.