CuAlO2, is a delafossite-type compound and is a known p-type semiconductor. Transparent CuAlO2 thin films "ere prepared using a sol-gel technique. The films with an Al/Cu atomic ratio of 1.0 consisted of CuAlO2 Cu2O, and CuO after heat treatment at 800degrees-900degreesC in nitrogen gas. The electrical resistivity of the film heated at 800degreesC was 250 Omega(.)cm.