A new sensitizing dye-semiconductor system comprised of perylene derivatives on SnO2 has been characterized. The tetracarboxylic acid form ("PTCA") of the commercially available dye perylene-3,4,9,10-tetracarboxylic dianhydride and the novel compound perylene-3,4-dicarboxylic acid-9,10-(5-phenanthroline)carboximide ("PPDCA") adsorb strongly to the surface of colloidal films of SnO2 and inject electrons into the semiconductor film upon absorption of light. A Nm of PPDCA on SnO2 yields a short circuit photocurrent density of 3.26 mA/cm(2), a photovoltage of -0.45 V, and an overall cell efficiency of 0.89% at one sun Light intensity. Estimates of the oxidation potential of adsorbed PPDCA indicate that it may also be useful in a water-splitting configuration. The results presented here indicate that the perylene-SnO2 system is a promising dye-semiconductor combination and warrants further study.