Several techniques are routinely used to fabricate arrays of microchannels embedded in crystalline silicon. They are commonly based on plasma or anisotropic etch of silicon and on subsequent wafer bonding to close the cavities on top. These techniques are quite complex and usually work on (110) oriented silicon wafers. In this paper we present an innovative microchannel formation process, entirely based on front side wafer silicon bulk micromachining, which allows us to produce rhomboidal microchannels embedded on (100) silicon wafers. Compared to the traditional techniques, the proposed process is very compatible with the standard microelectronics silicon technology. The kinetics of rhomboidal microchannel formation are monitored by cyclic voltammetry measurements and the results are compared with a detailed structural characterization performed by scanning electron microscopy. The effectiveness of this process is discussed in view of the possible applications in the microfluidic field. (C) 2004 The Electrochemical Society.