In this paper we were trying to analyze how Scopus subject categories of journals can influence processing and use of bibliographic data in bibliometric or scientometric research. The sample for this research was obtained from Scopus database as a result of the search strategies of scientific productivity and citations of social scientists from 15 European post-socialist countries (Bulgaria, Croatia, Czech Republic, Estonia, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia, Slovenia, Bosnia and Herzegovina, Former Yugoslav Republic of Macedonia, Montenegro and Serbia) for the period 1996-2013. The sample consisted of bibliographic records of 83, 059 papers published in 4, 896 journals. Each of 4, 896 journals, classified to social sciences according to Scopus' subject categories, was analysed and reclassified according to OECD- based Croatian classification of social sciences, by a subject specialists. The results of reclassification process were huge decreased, in number of journals, from initial 4, 896 it fell to 2, 744 titles, as well as number of papers (N=35653 papers), to only 42.9% of the initial number. In addition to a significantly smaller number of papers and journals, there are significant differences in the citations count. The obtained results confirm Wang & Waltman (2016) thesis that the accuracy of a classification system can seriously influence bibliometric studies.