Abstract Porous n-type Si has been used to fabricate PtSi Schottky detectors. The n-type Si substrates were made porous by anodic etching under ultraviolet radiation. The micrometer size pores were completely filled by Pt through electrodeposition. After annealing and subsequent etching of excess Pt a uniform PtSi layer was formed over the entire surface of the pores. The Schottky junction resulting from PtSi/porous Si surface was reverse biased and its response to 0.8–1.2 μm of radiation was determined in back illumination mode. Responsivities as large as 100 A/W at 0.8 μm, corresponding to a gain larger than 90 in efficiency, were obtained. This indicates that an internal gain mechanism such as avalanche multiplication is occurring in the porous samples, which is also corroborated by the general I– V characteristics. The use of these detectors as highly sensitive near IR detectors is discussed.