Over the years, different experimental techniques have been employed to prepared activated carbon-metal oxide composite materials. However, some of these methods entail cutting-edge equipment and long processing time which may result in the destruction of the carbon structure. Electroless plating, which is a simple and efficient method, have been used to deposit nickel oxide nanoparticles on activated carbon prepared from oil palm shell (OPS) using microwave –assisted CO2 activation. The nanocomposites have been heated at various temperatures (300, 400 and 500 oC) for 1 and 2 h. The prepared activated carbon has BET surface area and total pore volume of 574.37 m2 g-1 and 0.244 cm3 g-1, respectively. The optimum heat treatment temperature has been found to be 400 oC. Also, the weight percent composition of nickel has been shown to increase with increase in treatment time.