A process for preparing lithium nickeloxide (LiNiO.sub.2) for use as a positive electrode active material for a nonaqueous secondary battery, which comprises the steps of: (a) using as the raw materials a lithium compound and a nickel compound at least one of which has a melting point not higher than 300.degree. C.; i) in case where both of the lithium compound and the nickel compound have a melting point not higher than 300.degree. C., mixing the above two compounds after their melting, or mixing the above compounds, melting the mixture and mixing the melted mixture; ii) in case where either one of the lithium compound and the nickel compound has a melting point higher than 300.degree. C., mixing said one having a melting point higher than 300.degree. C. with the remaining one before or after its melting; (b)calcining the resulting mixture at a temperature of 700.degree. C. to 950.degree. C. in air or in an atmosphere containing oxygen in a higher concentration than an atmospheric oxygen concentration.