In this study, Cu2ZnSn(S,Se)(4) (CZTSSe) thin films were deposited by the single step thermal evaporation process using the sintered powder of CZTSSe on soda lime glass (SLG) and Si wafer substrates. The structural, optical, and electrical properties of deposited films were investigated. Current-voltage (I-V) in the temperature range of 250-350 K, capacitance-voltage(C-V) and conductance-voltage (G/w-V) measurements at room temperature were carried out to determine electrical properties of CZTSSe/n-Si structure. The forward bias I-V analysis based on thermionic emission (TE) showed barrier height inhomogeneity at the interface and thus, the conduction mechanism was modeled under the assumption of Gaussian distribution of barrier height. The mean barrier height and standard deviation at zero bias were obtained as 1.27 eV and 0.18 V, respectively. Moreover, Richardson constant was obtained as 120.46 A cm(-2) K-2 via modified Richardson plot and the density of interface states (D-it) profile was determined using the data obtained from forward bias I-V measurements. In addition, by the results of frequency dependent C-V measurements, characteristics of the interface state density were calculated applying high-low frequency capacitance (C-HF - C-LF) and Hill-Coleman methods.