Results of X-ray fluorescence measurements of new oxycarbonitrate superconductors MSr2Can-1CunOy (n = 1 or 2 and Al = Cu, C or NI) are presented. The experiments show that C atoms form a distorted CO3 oxyacid group with a partial substitution of copper and nitrogen atoms in the Af sites. Based on the comparison of nitrogen K alpha emission spectra and spectra of reference samples it is concluded that the CO32- group in (C,N)Sr2Can-1CunOy and (Cu,C,N)Sr2Can-1CunOy is substituted by the NO2- instead of the NO3- group. This induces the creation of hole carriers in these compounds. (C) 2001 Elsevier Science B.V. All rights reserved.