A unique piston-in-mold (punch-in-die) process, developed at the Capsule Pipeline Research Center (CPRC), University of Missouri-Columbia, USA, was used to study the compaction of the combustible components found in municipal solid waste (MSW) stream to produce a densified fuel. The compaction was performed under room temperature without binder and at pressures up to 138 MPa. The materials included waste paper, plastics (both film and hard products), textiles, and wood. They were compacted into 49-mm-diameter logs in different mixtures and under various moisture contents and pressures. The mixtures compacted include: (1) paper and plastic film, (2) paper and hard plastics, (3) paper and mixed plastics (both filmed and hard), and (4) paper, plastics, textiles, and wood. The properties of the logs, including density, abrasion resistance, impact resistance, combustion characteristics, and long-term performance were tested. The results show that the waste paper in the mixtures played a role of binder in the formation of the compacted logs. Moisture content and compaction pressure were two key parameters for producing good logs. For all these mixtures, a moisture content of less than 15% is necessary to produce dense (dry density equal to or higher than 0.8 g/cm(3)) and strong logs. A minimum compaction pressure of 70 MPa is needed for mixtures 1, 2, and 3, and 100 MPa for mixture 4. The logs made from the mixtures of the combustible wastes have a heating value equivalent to that of subbituminous coal, and can be cofired with coal in power plants.