The oxidation behaviour of 8090 AI-Li alloy sheet was studied after exposure for short times (<5 min) in laboratory air, moist air, moist argon and hydrogen at 530 ° C. Oxidation was greater at grain boundaries in hydrogen but not in air. Sites of rapid local oxidation (number density 9 to 8 x 103 cm -2) were associated with insoluble particles. Four types of growth morphology were identified with these sites. Some growths believed to be spinel, were 10 to 25/~m diameter and grew to ~ 1 mm in height at 2 #m sec -1 . Pits beneath these growths were 25#m diameter and 10 to 20#m deep. A qualitative model is proposed for rapid oxidation in AI-Li alloys and the effect of these sites on weight gain measurements, surface contamination and mechanical properties is discussed.