Heat transfer from a surface having constant heat flux subjected to oscillating flow in a vertical annular liquid column is investigated experimentally. The oscillation of water column in annuli is created using a piston cylinder mechanism. The experiments are carried out for four different oscillation frequencies, three amplitudes and three heat fluxes while the other parameters remain constant. The cycle-averaged values are considered in the calculation of heat transfer using the control volume approximation. Based on the experimental data, an empirical equation is obtained for the cycle averaged Nusselt number as a function of kinetic Reynolds number and dimensionless amplitude. (c) 2009 Elsevier Ltd. All rights reserved.