The Environmental Protection Agency is sponsoring development programs to identify automobile engines having low exhaust emissions. One approach being investigated is the Rankine cycle which includes a reciprocating steam expander as the prime mover. For maximum engine performance, high temperatures and pressures similar to modern steam power plant practice are required. For these operating conditions, liquid lubricants for cylinder and inlet valve lubrication are a limitation. Solid lubricants, to be investigated in this program, appear to offer long life at high temperatures. Potential system contamination problems from liquid lubricants introduced to the working fluid are also reduced. Phase I of this program includes the design of practical single cylinder reciprocating expanders for the purpose of evaluating solid lubricants and other supporting materials for use in a Rankine cycle automotive propulsion system utilizing a water base fluid.