Oscillating motion of fluid flow in a capillary tube can produce a nonlinear thermal boundary layer resulting in an increase of heat transfer coefficient. In the current investigation, an oscillating motion of fluid flow in a round tube was investigated to determine a triangular waveform effect on the heat transfer coefficient. An analytical solution of laminar Newtonian flow with a triangular pressure waveform was obtained. Results show that the heat transfer coefficient of the oscillating flow depends on the fluid properties and oscillating waveform. The triangular waveform of oscillating motion can result in a higher heat transfer coefficient. (C) 2013 Elsevier Ltd. All rights reserved.