The role of oxygen contamination in determining the properties, particularly the resistance, of the cosputtered tantalum disilicide has been investigated. As‐deposited films with silicon/tantalum atomic ratios in the range of 1.9 to 2.5 were monitored. There is no noticeable effect of the small amounts of oxygen (≲0.5 at. %) on the stress and the reactive ion etching characteristics of these films. The resistance, however, changed significantly due to the presence of oxygen even in a concentration as small as 0.02 at. %. The results are discussed in view of the changing Si/Ta ratio and oxygen concentration and the possible hopping electron conduction mechanism.