CZTS monograin powder samples were synthesized in CdI2 as flux material. The obtained materials were analysed by EDX, SEM, and Raman methods. It was found that Cd from flux was incorporated into the formed compound leading to the formation of solid solution Cu2Zn1-xCdxSnS4. The content of Cd in the compound was studied in the dependence of synthesis temperature and time. It was found that Cd content in the formed Cu2Zn1-xCdxSnS4 did not depend on synthesis duration at constant temperature and increased with temperature. The activation energy of the Cd incorporation process was estimated as 17.5 ± 2 kJ/mol.