Experimental investigation of a heat sink for cooling of electronic devices is performed, The objective is to keep the operating temperature at a relatively low level of about 323-333 K, using a dielectric liquid that boils at a lower temperature, while reducing the undesired temperature variation in the both streamwise and transverse directions. The experimental study is based on systematic measurements of temperature. flow and pressure, infrared radiometry and high-speed digital video imaging. The heat sink has parallel triangular microchannels with a base of 250 mum. Experiments on flow boiling of Vertrel XF in the microchannel heat sink are performed to study the effect of mass velocity and vapor quality on the heat transfer, as well as to compare the two-phase results to a heat sink cooled by single-phase water flow.