Diffuse reflectance Fourier transform infrared spectroscopy and photoluminescence measurements have been performed on porous silicon layers (PSLs) after different post-etch treatments : immediate drying under flowing N-2, rinsing in deionized water, and ethanol immersion. Layer composition and luminescence were also subsequently monitored during lengthy storage in ambient conditions. This study reveals a different surface composition and morphology arising from each post-anodization procedure, and no clear relation between composition and photoluminescence evolution of PSLs.