A novel Rankine cycle system configured to convert waste heat into mechanical and/or electrical energy is provided. In one aspect, the system provided by the present invention comprises a novel configuration of the components of a conventional Rankine cycle system; conduits, ducts, heaters, expanders, heat exchangers, condensers and pumps to provide more efficient energy recovery from a waste heat source. In one aspect, the Rankine cycle system is configured such that an initial waste heat-containing stream is employed to vaporize a first working fluid stream, and a resultant heat depleted waste heat-containing stream and a first portion of an expanded second vaporized working fluid stream are employed to augment heat provided by an expanded first vaporized working fluid stream in the production of a second vaporized working fluid stream. The Rankine cycle system is adapted for the use of supercritical carbon dioxide as the working fluid.