The present invention provides a waste heat recovery system, comprising a closed fluid circuit through which an organic motive fluid flows, heat exchanger means for transferring heat from waste heat gases to the motive fluid, means for flashing the motive fluid which exits the heat exchanger means into a high pressure flashed vapor portion, means for flashing liquid non-flashed motive fluid producing a low pressure flashed vapor portion, a high pressure turbine module which receives said high pressure flashed vapor portion to produce power, and a low pressure turbine module which receives a combined flow of motive fluid vapor comprising the low pressure flashed vapor portion and discharge vapor from the high pressure turbine module whereby additional power is produced.