The simultaneous flow of water, oil and gas is of practical importance for the oil and gas industry. These three phases are present in varying degrees of concentration in many oil and gas pipelines. In this work, a model has been developed to predict the values of the hold-up and pressure gradient for three-phase stratified flow prevailing in a horizontal pipeline. This information is usually the first step for analyzing the stability of stratified flow and developing transition criteria. The concept of extended velocity has been applied to compute the wall shear stresses in three-phase flow. The effect of process variables such as gas to liquid ratio, pipe diameter, oil viscosity and non-Newtonian character of oil on hold-up and pressure gradient has been studied to simulate the oil well conditions. Structural stability analysis was also carried out to check for the sensitivity of the model. (c) 2005 Elsevier Ltd. All rights reserved.