Experiments were condacted with water and surfactant flow in parallel triangular micro-channels. The study was based on systematic measurements of temperature and flow pattern by infrared radiometry and high-speed digital video imaging. Different flow patterns were observed simultaneously in various micro-channels al a fixed value of water or surfactant flow rates. Depending on flow and heat flux, pressure and temperature instabilities in the heated micro-channels were studied. This work develops a practical modeling approach for two-phase micro-channel heat sinks and considers also the effect of surfactants on convective boiling in micro-channels.