A technical and economic evaluation of a chemical cogenerative solid oxide fuel cell plant that uses methane (natural gas) as fuel is presented, The 100 MW electrical power plant produces simultaneously 0.21 x 10(9) fb of ethylene from the methane oxidative coupling reaction that takes place at the anodic electrode-catalyst of yttria-stabilized zirconia solid electrolyte cells, The technoeconomic evaluation gives an acceptable return on investment before taxes of about 21.5%. The economics are also compared to those of a conventional oxidative coupling chemical plant. The return on investment after taxes (ROIAT) is 13% for the fuel cell plant while for the equivalent conventional chemical plant it is about 14%. The most important contributors to the total cost are identified, Areas of possible cost reduction that could significantly increase the competitiveness of the fuel cell plant are also identified and discussed.