Phase equilibria were determined in the complete composition range of the SrO-Cr2O3-La2O3 system in air at 1223 K and under low oxygen pressure (high vacuum, p(O-2) approximate to 10(-9) bar). The (La,Sr)CrO3 perovskite phase is the only quasi ternary oxide phase stable in air. The quasi ternary Ruddlesden-Popper phases (La,Sr)(n+1)CrnO3n+1 (n = 1,2,3) were identified in addition to the perovskite phase in the samples annealed under low oxygen pressure. The solubility limit of strontium in the La1-xSrxCrO3 phase was determined at 1223 K as x = 0.10+/-0.02 in air and at 1873 K as x = 0.31+/-0.02 under low oxygen pressure. The crystal lattice parameters of the Ruddlesden-Popper phase LaSrCrO4 were obtained by the analysis of XRD patterns.