An ordered hexagonal mesoporous nickel oxide was prepared for the first time using sodium dodecyl sulfate as the surfactant and urea as the hydrolyzing agent. The resulting oxide showed mesoporous structure with pore size ranging from 4 to 7 nm. Calcination at different temperatures was carried out, and the mesoporosity did not collapse even after calcination at 773 K although the surface area decreased drastically (from 279 to 72 m 2 /g) and a broader pore size distribution was observed.