In this study, polycrystalline thin films of ternary AgIn5Se8 compounds with n-type conductivity were deposited on p-type Si substrates from the powder of a Ag3In5Se9 single crystal by a thermal evaporation technique. Transport and photo-transport properties of the In/n-AgIn5Se8/p-Si/Al sandwich structure were investigated by analyzing temperature-dependent dc current-voltage (I-V), and photo-response measurements carried out in the temperature range of 200-360 K. In order to obtain the series resistance (R-s) and shunt resistance (R-sh) values, the parasitic resistance (R-p = partial derivative V/partial derivative I) was analyzed for forward and reverse voltages. Devices showed very good diode behavior with the rectification factor of about 10(4) at 1.0 V in dark. The ideality factor n and the barrier height phi(b) values of the heterojunction diode were determined by performing different I-V plots. A space charge limited current method was used to determine the conduction mechanism at a high bias region. Spectral photo-response analyses showed a shifting of the band edge to the lower energies with increasing temperature.