Quaternary Cu2ZnSn(S,Se)4 compounds are promising semiconductor materials for absorber layer in thin film solar cells due to direct band gap in the range 1- 1.5 eV and high absorption coefficient (> 104cm-1) [1,2]. All constituents of these films are abundant, low cost and non-toxic. The highest conversion efficiency of Cu2ZnSn(S, Se)4 solar cell is till now 10.1% [3] The investigated Cu2ZnSnS4 thin films were grown by spray pyrolysis using the installation and method described in [4] with solution of H2O and C2H5OH with heightened concentration of pure chemical compounds at substrate temperature ~450°C (CZTS I) and were deposited by PVDcoevaporation (CZTS II), the Cu2ZnSnSe4 thin films were obtained by selenization of Cu2ZnSnS4 precursors at 500 °C for the time of 1 minute (CZTSe 1min) and 10 minutes (CZTSe 10 min). The structural characterization of the films was carried out by grazing incidence X-ray diffraction (GIXRD) using a PANalytical X’pert Pro MPD diffractometer with Cu−Kα -radiation (λ=1.54056 Å). The incident angle was chosen as 2o, a collection time of 17s/step and a step size of 0.02 o was applied. The Rietveld analysis of the diffraction data was performed using the FullProf software [5]. The structure model of kesterite (space group I 4 ) was used as a starting point for the refinement procedure. Lattice parameters obtained from the XRD patterns are in good agreement for the Cu2ZnSnS4 thin films grown by the two different methods, the values of lattice parameters of selenized Cu2ZnSnS4 thin films are increasing with increasing Se content, in dependence of the time of selenization, Table 1.tableFinancial supports from STCU # 5402 and from IRSES PVICOKEST – 269167 projects are acknowledged. [1] J.M. Raulot, C. Domain, J.F. Guillemoles, J. Phys. Chem. Solids 66 (2005) 2019. [2] P.A. Fernandes, P.M.P. Salomé, A.F. da Cunha, Phys. Status Solidi C 7 (2010) 901. [3] D. Aaron R. Barkhouse, Oki Gunawan, Tayfun Gokmen,Teodor K. Todorov, David B. Mitzi, Progress in Photovoltaics: Research and Applications 20 (2012) 6–11. [4] A. V. Simashkevich, D. A. Sherban, L. I. Bruk, A. Coval, V. Fedorov, E. Bobeico, Yu. Usatyi, Proc. of the 20th European Solar Energy Conf. 2005, Barcelona, pp. 980-982. [5] Juan Rodriguez-Carvajal and Thierry Roisnel, www.ill.eu/sites/fullprof/