Submicron and stoichiometric LiNiO2 was successfully crystallized at low temperatures using Pechini method, which was developed to crystallize mixed cation oxide from organic precursors. The crystal structure and the effect of oxygen were investigated in this study. The synthesis of LiNiO2 was described as the decomposition of citrate into Li2CO3 and NiO, which subsequently formed LixNi2 . xO2 at temperatures higher than 500 degreesC in air. When the precursor was calcined at 300 degreesC in O-2 atmosphere, Ni2O3, NiO, Li2CO3 and LixNi2-xO2 were found. Structural analysis showed that the crystallization of LixNi2-xO2 was significantly enhanced by the presence of oxygen at lower temperatures. Li0.98Ni1.02O2 and Li0.85Ni1.15O2 were obtained in O-2 and air atmosphere, respectively. The I(003)/I(104) ratio of LixNi2-xO2 formed is higher in pure oxygen (1.43) than that in air (1.2). Thus, it is expected that LixNi2-xO2 synthesized in Oz atmosphere exhibits better electrochemical properties than that synthesized in air.