Poly[2-methoxy-5-(2 '-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) thin layer was deposited on silicon nanowires (SiNWs) by electroless dipping method. SiNWs were obtained using Ag-assisted chemical etching process. Scanning Electron Microscopy (SEM) images reveal a vertical alignment of the SiNWs as well as the formation of MEH-PPV layer on their surfaces. The presence of MEH-PPV polymer on the SiNWs surface was confirmed by Energy-dispersive X-ray (EDX). Current-Voltage (I-V) measurements were performed for the electrical characterization of Ag/MEH-PPV/SiNWs diodes before and after annealing. The ideality factor (n), the barrier height (phi(b)) and the series resistance (R-S) are determined using the Cheung method. The diode parameters are strongly affected by the immersion duration in MEH-PPV solution as well as the annealing temperature. The rectification rate of the diodes was increased by MEH-PPV deposition. The annealing temperature has a great influence on the diode parameters by the thermal activation of carriers at Ag/MEH-PPV and MEH-PPV/SiNWs interfaces. I-V characteristics show an ohmic character for temperatures above 250 degrees C. The electrical parameters such as equivalent carrier concentration (N-D) and built-in voltage (V-b) and other values of phi(b) are calculated from Capacitance-Voltage (C-V) measurements.