This paper presents CFD predictions for the evaporation in a microchannel for inlet mass flux in the range 10 up to 100 kg/m²s, under atmospheric pressure. The model solves the Navier-Stokes equations along with the energy conservation equation and the species transport equations; the Volume of Fluid (VOF) methodology has been utilized to capture the liquid-vapor interface using an adaptive local grid refinement technique aiming to minimize the computational cost and achieve high resolution at the liquid-gas interface region. A two dimensional microchannel of length 1000µm and hydraulic diameter of 100µm was developed in ANSYS FLUENT 13. Results were analyzed in term of the variation of volume fraction of vapor at different locations along the microchannel.