In this work, a facile approach is presented to synthesis Pt-Cu nanoalloy with time scale of a few minutes at room temperature. Pt-Cu nanoalloy was supported on the surface of porous silicon (PSi) powder by a simple in-situ redox reaction between PtCI62 /Cu2+ and PSi, in hydrofluoric acid solution. The morphological, chemical and electrochemical properties of the prepared nanostructure were characterized using field emission scanning electron microscopy, X-ray diffraction spectroscopy, energy dispersive X-ray spectroscopy, cyclic voltammetry and chronoamperometry. Then, the electrocatalytic activity of Pt-Cu@PSi toward hydrazine oxidation and hydrogen peroxide reduction was investigated and were compared with Pt@PSi and Cu@PSi. The results showed that Pt-Cu@PSi has higher electrocatalytic for both the analytes. To have better behavior of the electrocatalyst for the detection of hydrazine and hydrogen peroxide, Pt-Cu@PSi modified carbon ionic liquid electrode (CILE) was fabricated. Using the proposed electrochemical sensor, hydrogen peroxide could be measured in the range of 0.5-1280 mu mol L (1) with detection limit of 100 nmol L (1), whereas hydrazine could be measured in the range of 0.20-1680 mu mol L (1) with detection limit of 50 nmol L (1), using chronoamperometry technique. Finally, the prepared electrochemical sensor was employed to determine hydrogen peroxide and hydrazine in real samples with satisfactory results. (C) 2015 Elsevier Ltd. All rights reserved.