*† The following presents flow boiling oscillation characteristics in two silicon microchannel heat sink configurations aimed at micro/nano- spacecraft thermal management. One is a conventional heat sink with 45 parallel channels, whereas the second is similar except with cross-links at 3 locations along the channels. Data are presented over a flow range of 20 to 50 ml/min using distilled water as the working fluid. The heat sinks have a footprint area of 3.5 cm 2 and contain 269 µm wide by 283 µm deep DRIE channels. Flow boiling oscillations are found to be similar in characteristic trends between the two configurations, showing a decreasing frequency with increasing heat flux. The oscillation amplitudes are relatively large, but identical in frequency and phase between the inlet and outlet temperature, inlet pressure and pressure drop. Data for the standard heat sink at two different inlet temperatures and various flow rate, show an increasing frequency trend with decreasing inlet temperature, whereas an increasing frequency with increasing flow rate. Although limited data is presented on the cross-linked configuration, this work presents a first glimpse of their characteristics under two-phase flow conditions.