A quantitative study of the variation of stoichiometry with temperature near the surface of SrTiO3 is conducted. Surface concentrations and the strontium depth profiles are obtained using Rutherford backscattering spectrometry and Auger electron spectroscopy. While the Auger electron spectroscopy demonstrates that the surface is strontium rich after annealing at temperatures ranging from 800 to 1300-degrees-C, Rutherford backscattering measurements show no evidence of strontium enrichment beneath the surface unless the crystal is annealed at 1300-degrees-C or higher. The observations indicate that changes in surface chemistry involve two processes : sublimation and segregation; which play different roles at different temperature ranges.