LiNi1-yMyO2 ( M = Ga, In and Tl, y = 0.010, 0.025 and 0.050) with small y were synthesized by the combustion method by calcining in an O-2 stream at 750 degrees C for 36 h. XRD analyses, SEM observation and measurement of the variation of discharge capacity with the number of cycles were carried out. All the samples had the R (3) over barm structure and LiNi1-yInyO2 contained LiInO2 phase as an impurity. Among LiNi1-yGayO2 the sample with y = 0.025 had a relatively large first discharge capacity (172.2 mAh g(-1)) and relatively good cycling performance ( discharge capacity 140.3 mAh g(-1) at n = 20). For LiNi0.975M0.025O2 (M = Ga, In and Tl), the first discharge capacity decreased in the order of the substituted element Ga, In and Tl. The variations of cation mixing and hexagonal ordering with the substituted element ( decrease in I-003/I-104 and increase in R-factor from M = Ga through M = Tl) are considered to lead to the behavior of the first discharge capacity with the substituted element. LiNi0.975Tl0.025O2 had the smallest degradation rate of the discharge capacity.