Cd-Sn or In-Sn oxide were prepared by thermal oxidation of as-sputtered films from a Cd-Sn or In-Sn alloy target in an Ar-O_2 atmosphere. The films were transparent in the visible region and were electrically conductive. The optical transmission and electrical resistance were examined as a function of the thermal oxidation condition, such as temperatures and time. The lowest resistivity of Cd-Sn oxide and In-Sn oxide was 5.1×(10)^<-4>Ω・cm and 5.4×(10)^<-4>Ω・cm, respectively. The highest average optical transmission of both oxide films was about 90% and 93% in the visible region, respectively.