A microscale chip cooling system for a heat dissipating item, such as Intel's Pentium brand microprocessor. The system includes a 40 millimeter by 40 millimeter thermally insulated housing including a base and a cover. The system also includes a thermally conductive evaporator. The evaporator is adapted to be attached to a heat source such as the microprocessor. The cover includes inlet and outlet ports and the base includes a capillary passage. A refrigerant or heat transferring fluid is pumped or past through the passage before making a sudden expansion in an expansion zone just before passing to an evaporator chamber. Pool and flow boiling and forced convection may occur in the evaporator chamber as heat is transferred from the microprocessor through the thermally conductive evaporator to the refrigerant. The refrigerant then returns to a compressor to repeat the cycle. The system is extremely small and very efficient.