In this thesis syntactic functions of the infinitive and the supine in the texts written in Croatian Church Slavonic Language are systematically described and presented. In the first chapter some general remarks about the infinitive and supine have been made, mostly from the typological perspective, along with the diachronic sketch of their development in Indo-European and Slavic languages. The second chapter summarizes the basic knowledge of Croatian Glagolitism, its monuments, and the Croatian Church Slavonic language. It also gives complete inventory of the text material on which the research was conducted. The third chapter briefly provides an overview of the up-to-date research of infinites and supines in the Croatian Church Slavonic. In the most extensive fourth chapter, basically on the traditional grammar grounds, a thorough analysis of syntactic functions of the Croatian Church Slavonic infinitive is presented, starting from the infinitive as predicate or part of the predicate, moving to its function of object complement, secondary predicate, adverbial complement and complement to nouns and adjectives, and finishing with its subject roles. At the end of this chapter Croatian Church Slavonic constructiones of dative cum infinitive and accusative cum infinitive are discussed. Final chapter analyses instances of supine use. Where possible, conclusions are drawn regarding the (morpho)-syntactic development of the spoken Croatian language (e.g. development of Future I in Old Chakavian), while comparisons within the research corpus and comparisons with Old Church Slavonic as described in literature has shown that syntactic features that are considered merely literary forms of expression in Old Church Slavonic, besides the accusative cum infinitive, are in Croatian Church Slavonic merely preserved and transmitted through scribal practice, and that only Slavic (i.e. Croatian, Chakavian) and Latin features are in live use in later, Croatian Church Slavonic, translations. Particularly interesting is the ratio between the dative cum infinitive and accusative cum infinitive constructions, since it became clear that in the Croatian Church Slavonic the withdrawal of the dative cum infinitive has resulted in the widespred use of the accusative cum infinitive. Three linguistic features that distinguish Croatian Glagolitic breviaries from missals have been singled out: »periphrastic conjugation«, supine and dative cum infinitive construction. Their occurance only in breviaries leads to the conclusion that revisions of Croatian Glagolitic breviaries and missals should be separated in general, and due to the fact that supine and dative cum infinitive are more archaic features preliminary conclusion is drawn that Croatian Glagolitic breviary precedes Croatian Glagolitic missal in age.