The Slavic affricate represented by /č/ is tacitly or explicitly assumed to be /
/ for all Slavic languages. In this paper we revise the affricate inventories of Polish and Czech, showing that the symbol /č/ stands for two different sounds: the palatoalveolar / / in Czech and the retroflex / / in Polish. This conclusion is supported by acoustic results for Polish and Czech data. The fact that COG (centre of gravity) values of frication are not significantly different for Polish and Czech /č/ appears a bit surprising especially in light of the fact that COG is generally seen as a parameter contributing to the distinction of fricatives (including sibilants, see e.g. Gordon, Barthmaier & Sands 2002). Our results show that other parameters such as duration of the frication phase, F1 and F2 of the following vowel as well as spectral slopes are more reliable cues for distinguishing the small differences between affricates examined here.