The flow and heat transfer behaviour of liquid-liquid Taylor flow is examined by performing both experiments and CFD simulations for 1 and 2 mm vertical tubes with constant wall heat flux boundary conditions. Water and hexadecane are used as the disperse and continuous phases, respectively. The measured heat transfer coefficients are extremely sensitive to experimental uncertainties but, are in overall good agreement with the simulations. The simulations confirm the strong dependence on the flow conditions seen in the experiments. A generalised model of heat transfer in gas-liquid and liquid-liquid Taylor flows is developed from a combination of resistances for wall-to-film, film-to-slug and film-to-bubble or droplet. Good estimates for these individual resistances are described and validated. The overall heat transfer coefficient obtained by a rigorous weighting of the individual resistances correlates the entire set of CFD (liquid-liquid) and experimental (gas-liquid) data with 20% relative standard deviation. The model captures the complex parametric dependencies and sensitivities in the data. (C) 2015 Elsevier Ltd. All rights reserved.