Laboratory scale open-top lysimeters were used for evaluating methane oxidation capacity of stabilized wastes. The acrylic col-umns (Fig. 1) have a diameter of 0.15 m and a height of 1.0 m. They were filled with stabilized wastes obtained from a solid waste dis-posal site in Thailand which has been in operation for more than 20 years. Atmospheric oxygen can be facilitated into the waste layer through natural diffusion at the top of lysimeters. The solid wastes composed of 52.8% plastic wastes and 47.2% of fine fraction (stabilized organic wastes) and their chemical characteristics are