We present here a theoretical and experimental study of two-phase flow in a heated capillary tube. The flow parameters of a single-phase liquid, two-phase liquid-vapor, and single-phase vapor were analyzed in the frame of a one-dimensional model. The pressure, temperature and vapor quality measurements were carried out in a pipe of 1.0 mm inner diameter at various values of heat fluxes and mass flow rates and compared with theoretical predictions. The evolution of the bubble volume was studied both theoretically and experimentally. Using infrared technique, the temperature distribution on the heated tube surface was studied for various flow regimes. (C) 2003 Elsevier Ltd. All rights reserved.