The results of studies related to the oxidation of W and its alloys are studied. The pressure of WO3 polymers over WO2 was measured in a W Knudsen cell and found to agree with measurements in a Pt cell. Literature data for WO2 WO3 were combined with vapor pressures determined in this project to give thermodynamic values for W18O49 and W20O58. W oxidation rates were measured from 800 to 1700 C and in O pressures between 0.2 and 0.02 atmospheres. The effects of O pressure indicate that the rate may be governed by O dissociating to atoms at the reacting surface. The oxidation rate is demonstrated to be independent of the oxide evaporation rate. All of the evidence indicates that if an oxide barrier layer is present at temperatures above 800 C it must be very thin. Studies on the oxidation of Ta - W alloys between 800 and 1200 C indicate that the 50-50 alloy has the greatest oxidation resistance, oxidizing at a rate as much as 10 times slower than W alone.