A one-dimensional model of evaporation from V-grooved microchannels is presented herein. The integrated model incorporates the evaporation from the capillary as well as the transition region of the extended meniscus. The amount of evaporation from these two regions are calculated as function of the input heat flux, groove geometry and the liquid-solid combination. The evaporation from the capillary meniscus region is found to be substantially higher than that from the extended thin film region. The effects of the groove geometrical parameters on the performance (e.g., critical heat flux) of the microchannels have been studied. It has been found that including the specific heat requirement in the model equations has negligible effect on the evaluated parameters.