An experimental study was carried out to investigate the transient response of a thermal microsystem to both a step change and a square wave pulse change in heat flux. The microsystem consisted of a single microchannel etched on a silicon microdevice that was bonded to a Pyrex wafer. A thin-film titanium heater was deposited on the Pyrex substrate. The heater acted as the power source as well as the resistance temperature device. The influence of flow convection on the transient response was studied for two fluids: air and HFE-7000. The effects of heat flux, Reynolds number, fluid properties, and pulse parameters (amplitude, width, duty cycle) on the transient temperature response were identified. The temperature response consisted of an initial rapid temperature rise followed by slower convection dynamics. For longer pulse widths, the temperature of the microdevice reached steady state. Higher order dynamics were identified at the beginning of the temperature response. Convection dynamics were approximated as a first-order response, and the effects of Reynolds number and fluid properties on the time constant of the first order response were identified. (C) 2015 Elsevier Ltd. All rights reserved.