The effect of varying lanthanum composition upon the formation of the nonsuperconducting La1.67Sr0.33Cu2O5-delta and the stoichiometry variation tolerance of the ternary system La2-xSrxCuO4 (with x = 0 and 0.15) were investigated using a variety of techniques. Results indicate that total conversion to La2CuO4 from freeze-dried precursors with an La:Cu = 2.00 : 1 ratio is achieved after sintering (1253 K, 12 h) and annealing in oxygen (773 K, 6 h). Small variations in the stoichiometry of solids La2-xSrxCuO4 with x = 0 and 0.15 were detected. Lanthanum-deficient composition in the ternary system induces the formation of the non-superconducting phase whose stoichiometry is better represented by La1.60Sr0.40CU2O5-delta. The temperature-programmed reduction profiles of the cuprates can be associated with the formation of more or less stable intermediates.