Advanced solar cells and other optical detection devices incorporate surface texturing to reduce optical reflection and enhance absorption. Using electrochemical etching techniques, porous silicon surfaces are fabricated. Thin (pore depths less than 1 ?m) and thick (pore depths greater than 5 mm) porous silicon surfaces are optically characterized in terms of their ability to reduce optical reflectance. Three regions of the optical spectrum were investigated: visible (500 to 900 nm), near-IR (1.25 to 2.5 ?m), and mid-IR (2.5 to 12.5 ?m). A highly polished, single-crystal silicon wafer was used as a reference surface. It was determined that thick porous silicon manifested superior results compared to the thin porous silicon, demonstrating a 91% total reflectance reduction in the visible region, a 7% reduction in the near-IR range, and a 53% reduction over the mid-IR wavelengths.