The expectations of hotel guests, together with their behavior, have been changing drastically ever since almost all of them have owned a smartphone or tablet. The amount of time spent on mobile applications has increased tremendously, and as mobile operators are making it easier to use mobile devices when abroad, people can stay connected no matter the time or the place. Not only can the diffusion of mobile technology help to improve the user experience, its application also generates benefits for hotels, in terms of operations as well as finance. Based on these facts, it may be said that the importance of mobile technology and, in turn, mobile applications is huge and meaningful in the context of modern hotel business operations. Mobile technology enables users to access information and applications anytime and anywhere, thus ensuring greater flexibility in communication, cooperation and information sharing. The strategic importance of mobile technology cannot be underestimated, considering that the rapid pace at which mobile technologies are being adopted and improved creates opportunities for new, innovative services that can be provided through mobile devices. As mobile and wireless solutions have become an integral part of everyday life, simplicity, accessibility and easiness-to-use have today transformed mobile technology and mobile applications into an exceptionally important tool for hotel enterprises, helping them to distribute information, simplify processes and enhance productivity and sales in general. Hotel mobile applications on mobile devices like the iPhone, Android and Blackberry can help to increase interaction with end users, share information faster and more efficiently, and ensure guest feedback in real time, Also, the use of mobile applications for mobile devices sends a powerful message to the public that hoteliers are abreast of modern world trends in business and that the services they provide are of high standards and quality. If a hotel enterprise is to perform successfully on the increasingly discerning domestic and foreign tourism market, it needs to direct its attention to new ways of carrying out business processes, promotional activities and sales activities, as well as new ways of communicating with its current and future guests. To a great extent, hoteliers are preoccupied with the problem of how to sell more rooms, more food and beverages, without considering how to make efficient use of marketing channels. Many hotels continue to use out-dated and ineffective marketing channels. Talking about modern hotel business operations, without taking the importance of mobile applications into consideration, is almost inconceivable. All enterprises, hotels included, have accepted the fact that, similar to several years ago when they realized that embracing and developing a presence on the Internet was imperative to business operations, it is today essential to integrate the e-business concept throug mobile devices, with mobile applications indisputably being one of the best ways of achieving such a presence and conducting e-business. Mobile applications provide hoteliers with completely new way on communicating with their guests on an individual level, thus increasing guest satisfaction and loyalty on the one hand and hotel revenue on the other. In modern hotel business operations, the presence of mobile applications makes it possible to book accommodations using mobile devices, either through online booking platforms or hotel mobile applications. Accommodation revenue accounts for the largest and most important share of overall revenue of a hotel or hotel chain. In addition to selling accommodation capacities via mobile applications, additional sources of revenue can also be found in various offerings and services marketed directly to application users.That guests want top-quality service and experiences is a constant in the hotel industry. Mobile technology, however, has changed the perception of hotel guests and how they experience what is good. To come to closer terms with their present and future guests, hotels need to continuously monitor trends on the ever more discerning and burgeoning tourism market and adapt to the development of new technologies to remain competitive. It is the author’s opinion that hotels in Croatia are insufficiently present on mobile devices through mobile applications. Hence, this study, concerning the meaning and importance of mobile applications in hotel operations, seeks to answer the questions: To what extent are applications present? How are they used? What is their role in modern hotel business operations and in the hotel industry in general? With the objective of proving that the proper use of mobile technology via well-designed mobile applications in the hotel industry can, to a considerable extent, facilitate access to target markets, ensure the better dissemination of information and help to improve a hotel’s presentation and sales, the paper presents the results of research conducted showing the extent to which, and the ways in which, mobile applications are used in the Croatian hotel industry. Hence, a model (4M) was prepared and designed for developing multimedia mobile applications for hotel businesses. In addition, the individual elements of mobile applications,with corresponding modules of the proposed 4M model, were systematically analysed as part of the research. Within the research framework, at the very beginning of the research process, the author presents and proposes his own integrated conceptual 4M model for developing hotel mobile applications, with detailed descriptions of and explanations for each module and its associate sub-modules and their elements. The proposed conceptual model comprises nine separate modules, 33 sub-modules and 143 model elements. The name “4M model” stands for Model of MultiMedia Mobile applications for hotel businesses.For the purpose of research in this doctoral dissertation, the categorisation of tourism facilities, hotels, campsites and marinas in Croatia, published on the website of the Ministry of Tourism of the Republic of Croatia (2016), was used as a framework for sample selection. Due to issues related to the research subject as well as to the complexity of the task and the desire to draw as accurate as possible conclusions that must be based on qualitative and exact results of the research process, all four-star and five-star hotels in Croatia were included in the research sample. The sample consists of 264 four-star hotels and 35 five-star hotels, ranked by county. The hotels selected for the sample account for 45% of all categorised hotels in Croatia. The four-star hotels are distributed across 18 counties, while all five-star hotels are located within only five counties. For the purpose of gathering good-quality and reliable input data needed for empirical research, the responsiveness of the selected hotel websites in the sample was tested using Google’s Mobile-Friendly Test. Research was conducted from March to September 2016. For the purpose of research, data were collected from the websites and mobile applications of all hotels (providing they had the latter) selected for the sample. It was necessary for the author to download all the mobile applications of hotels in Croatia to his mobile device (and to register, if required) in order to analyse all application modules, thus obtaining the most accurate and relevant data for research. Data analysis and processing was carried out by comparing all the modules of hotel mobile applications with the proposed 4M model modules and elements. Data were classified by hotel category and by county. Access could not be gained to the websites of certain hotels, which were therefore not taken into consideration in data analysis and processing. The comparative method and the analysis method were applied to investigate, study, compare and analyse in-depth the existing state of the presence and use of mobile applications in the Croatian hotel industry. The SPSS 23.0 software package for statistical data processing was used to process the data collected. Descriptive statistics (arithmetic mean, standard deviation) and bivariate statistical analysis (t-test, ANOVA) were used to process and analyse data gathered by the comparative method. With the aim of proving the hypotheses formulated, a combination of scientific methods were used in the scientific research and presentation of research results. The scientific research methods applied were determined by the issues, possibilities and circumstances in which research was conducted. The results obtained by empirical research are indicative of hotel facility managers who seek to improve hotel performance by introducing new technologies; they can also be of help to all stakeholders in the hotel industry, in particular to hotels that want to become and remain competitive in the market. Also based on empirical research, proposals, suggestions and incentives are put forward, which could be directly and practically applied in various business processes, in particular in the field of hotel sales and marketing, with emphasis on a two-way communication process between guests and a hotel in real time.