Magnetoresistance properties of compounds with the same formula La0.7−xGdxCa0.3MnO3+δ (x=0, 0.04) but synthesized by the solid-state reaction method from different starting materials are studied. Nearly stoichiometric compounds are obtained when La(OH)3 is used for sample preparation. However, under the same condition, La2O3 causes considerable oxygen deficiency in resulting samples, characterized by a broad metal–semiconductor transition far below the magnetic transition. Inhomogeneous distribution of the oxygen content in compounds (an inhomogeneity beyond the detection of powder x-ray diffraction) can occur when both La2O3 and La(OH)3 coexist in the starting materials, leading to two metal–semiconductor transitions which are obviously developments of those in compounds prepared respectively from La2O3 and La(OH)3, and one magnetic transition corresponding to the upper resistive transition.