The first part is an experimental study of Ac. conduction and dielectric behavior of CdInGaSe4 defect chalcopyrite. CdInGaSe4 thin films were obtained by the thermal evaporation method. Measurements were investigated at temperatures (292.9–393.4 K), thicknesses (71–198 nm) and frequencies (100–1 MHz). The ac. conductivity σac.(ω) is temperature dependent and discussed by the correlated barrier hopping model CBH. Values of dielectric constant ε1(ω) and loss ε2(ω) are increased by temperature and decreased by frequency. The second part introduces estimation of ac conductivity and dielectric properties of CdInGaSe4 using adaptive neuro-fuzzy inference systems (ANFIS). Experimental data is used as inputs. Takagi-Sugeno type of ANFIS model is trained. The optimal networks are accomplished using MATLAB. ANFIS modeling outputs provide excellent results. Error values support the success of the modeling process. According to this research, the ANFIS technique is considered a successful tool to predict ac. conductivity and dielectric properties of CdInGaSe4.