The influence of concentration, vehicle, dextrose and temperature on the stability of sodium oxacillin solutions was determined using a chemical kinetic approach. Sodium oxacillin degraded faster in dextrose solution than in sodium chloride injection. This finding was attributed to the catalytic effect of dextrose on sodium oxacillin hydrolysis. Solutions of 1-50 mg/ml oxacillin in each vehicle were found to be stable for 24 hours at 23 C. The degradation of sodium oxacillin in various dextrose solutions was independent of oxacillin concentration, and followed first order kinetics.