Several sodium molybdenum oxides with different structures were prepared by acidification of Na2MoO4 solutions with 1-3.5 N of strong acids (HCl, HNO3) at 100 degrees C followed by heat treatment. Structural and compositional analyses of the oxides show that their structures were determined by preparation conditions such as acid type and concentration, and heat-treatment temperature. The electrochemical intercalation of lithium into these oxides was attempted using them as the positive electrode materials for secondary lithium batteries. The results show reversible lithium intercalation and electrochemical performance that greatly depends on the oxide structure and composition.