A theoretical model to predict critical heat flux in long, rectangular, curved channels is presented. Development is analogous to a model for long, straight channels previously proposed by the present authors. The model is based on the observation from a flow visualization study that vapor assumes a wavy, periodic distribution along the heated concave wall just prior to CHF such that liquid-surface contact is restricted to the troughs of the wave, called wetting fronts. When the idealized oscillatory liquid-vapor interface is lifted off the surface liquid can no longer rewet the surface to remove heat and CHF ensues. This lift-off of the interface occurs when vapor momentum emanating from a wetting front due to vigorous boiling overcomes the pressure force which serves to hold the interface in contact with the surface. A separated flow model, interfacial instability analysis, heater energy balance, lift-off criterion and flow visualization study combine to form a mechanistically-based CHF model for long, curved surfaces. The model predicts curved channel CHF data to within a mean absolute error of only 4.0% at near-saturated conditions for velocities up to 10 m s(-1), corresponding to centripetal accelerations reaching 315 times Earth＇s gravitational acceleration. The model accurately reflects the enhancement in CHF that curvature provides by offering predictions that are greater than the corresponding straight channel model predictions.