Nominalization is the process and the result of this process by means of which a sentence structure is placed in a different sentence structure in the position reserved for a nominal construction. In the process of nominalization the componential sentence changes into the attributive determinative syntagm. The initiative role in this syntagm is played by the substantive verbal, actional, abstract. The aim of this paper is to present three aspects of the nominalization: 1. Which phenomena will be the subject of analysis, i.e. what is the subject of interpretation, because nominalization is interpreted in various ways. 2. It must characterize the mechanism of nominalization in Polish and Slovak as a systems phenomenon. 3. Nominalization in texts in the languages needs to compare acceptability of nominalization in various functional styles which is related to different historical development of Polish and Slovak.