Oxygen tracer diffusion coefficients of selected compositions in the La1-xSrxMn1-yCoyO3 +/- delta perovskite oxide system have been measured by means of the Isotopic Exchange Depth Profile method (IEDP). O-18/O-16 exchange anneals were performed at various temperatures between 600 degrees C and 1000 degrees C (P-02 similar to 1 atm), and the subsequent O-18 diffusion profiles determined by Secondary Ion Mass Spectrometry (SIMS). It was seen that, in general, the oxygen tracer diffusivity of these materials increases significantly with strontium site fraction, x, and cobalt site fraction, p. This was attributed to variations in the site fraction of oxygen vacancies, with approximately constant isothermal vacancy diffusivities. The activation enthalpies for oxygen tracer diffusion were also found to be strongly dependent upon composition.