This paper deals with forced fluid flow in heated micro-channels with a distinct evaporation front. A simple one-dimensional model of the flow is proposed. The effect of a number of dimensionless parameters such as Pe, Ja, and dimensionless heat flux, on the velocity, temperature and pressure within the liquid and vapor domains has been studied, and the parameters corresponding to the steady flow regimes as well as the domains of flow instability are delineated. An experiment was conducted and demonstrated that the flow in micro-channels appears to have two distinct phase domains, one for the liquid and the other for the vapor, with a very short section of two-phase mixture between them. (C) 2001 Elsevier Science Ltd. All rights reserved.