Prepositions are an invariable type of words that serve as a supplement to the case system and are usually found before words in the case form and express the mutual relationship between objects, beings and phenomena. Together with other types of words, prepositions form an essential part of the grammar or syntax of the Croatian standard language. The theoretical part of this paper discusses the definition of prepositions, the divisions of prepositions, and then the expression of space with prepositional-case is explained. The second part of the paper presents the research part conducted on the spatial prepositional-case expressions. 75 respondents took part in the research, and an equal number of respondents from Zadar and Vukovar were randomly selected (60 in total). The research was carried out through a questionnaire that contained sixteen sentences that had to be filled out with the appropriate case form of the given catering facility. The results of all the respondents were presented, and then the answers were broken down according to the following criteria: gender of the name, origin of the name, structure of the name, preposition governing the case form and the type of default occurrences. The aim of the research was to determine whether there is a difference in the production of case forms in spatial prepositional-case constructions in which one-member and two-member names of catering establishments from the area of Vukovar and Zadar are present, and whether there is a deviation from the norm of the Croatian standard language. The purpose of the research is to determine and explain the most common errors of respondents when producing prepositional-case expressions, and an attempt will be made to explain the differences between respondents from Vukovar and Zadar when producing default constructions. The results of the research confirmed the difference between the two groups of respondents. The respondents from Vukovar were more successful in producing spatial prepositional-case expressions. The biggest difference was observed in the production of constructions with the accusative and the locative, where in most cases the respondents from Zadar produce the construction incorrectly and use the genitive case. In order for the conclusions to be considered representative, it is necessary to repeat the research on a larger sample of respondents.