Tracer diffusion coefficients in La1-x SrxFeO3, x=O and 0.1 from 900 to 1100 degreesC for both A- and B-site diffusions were examined with secondary ion mass spectrometry (SIMS) applying Y3+ and Cr3+ as tracers. In both compositions, the B-site diffusion, represented by Cr, was found to be faster than the A-site diffusion, represented by Y. The obtained activation energies for bulk diffusion in La0.9Sr0.1FeO3 were 168+/-24 kJ/mol for the Y tracer and 150+/-30 kJ/mol for the Cr tracer. The O-18-tracer diffusion coefficients were found to be significantly higher in La0.9Sr0.1FeO3 compared with LaFeO3.