Co-P-MCM-41 catalyst was prepared by introduction of cobalt nitrate and phosphoric acid during gel-preparation for the synthesis of MCM-41. The catalyst, which was found to have very high surface area (995m²/g), was tested for the one step liquid oxidation of cyclohexane to adipic acid using a semi-batch autoclave reactor (without addition of any promoter and solvent) at 115℃ and in a flow of 5 bar of oxygen. The effect of the amount of catalyst on the induction time, catalytic conversion of cyclohexane, and selectivity to adipic acid was investigated. Depending on the amount of catalysts used in the reaction (from 0.1 to 3.0 g), an induction period from about 100 min to less than 10 min, cyclohexane conversion from 30 to 99 %, and a selectivity to adipic acid from 15 to 40%, could be achieved using Co-P-MCM-41 as the catalyst.