In this study, phase changes associated with liquid column oscillation (latent heat transport) were experimentally investigated in order to understand the heat transport mechanism in pulsating heat pipes (PHPs). In the experiments, a channel was partially charged with working fluid to form a liquid column after the channel was evacuated. To investigate the thermal-hydraulic phenomena in actual PHPs, a forced oscillator caused the liquid column to oscillate sinusoidally in the channel under various oscillating conditions. Wall temperatures, vapor temperature, and vapor pressure were measured under several liquid column oscillation conditions. It was shown that liquid film plays an important role in latent heat transport; moreover, the liquid column plays the role of a switch in phase changes on the liquid film, according to the relationship between wall temperature fluctuations and the displacement of the tip of the liquid column. In addition, it was found that evaporation and condensation on the liquid film occur simultaneously. These experimental results helped to clarify the details of latent heat transport in PHPs. (C) 2018 Elsevier Ltd. All rights reserved.