The half-coil jacketed vessels find an extensive use in the chemical process industries for the process heating and cooling. The experimental studies of cooling of liquid using half-coil jacket is reported in the present work. The experiments are carried out for flow of coolant through half-coil jacket under both laminar and turbulent flow conditions. Correlations have been developed for the heat-transfer coefficient for the half coil jacket. A mathematical model for the half-coil jacketed system is proposed by developing the differential energy balance equations for both shell and coil side. In the model, the coil side is divided into the definite number (n) of mixing sections. The value of n is found out through dimensionless variance obtained from the transient cooling water temperature data and is equal to three for laminar and one for turbulent flow conditions. The equations were solved by semi-Implicit Euler method to predict the shell side and coil side temperature. It is found that the model predictions are in satisfactory agreement with the experimental data. (c) 2006 Elsevier B.V. All rights reserved.