We present the results of an experimental investigation of the evaporation of a liquid meniscus in a high aspect ratio micro-channel. The study investigates evaporation rates of a stationary liquid meniscus in a high aspect ratio microchannel, the wall of which is electrically heated using transparent resistive coating. Four different liquids are used as working fluids. We report on the dependence of the measured overall evaporation rate on the applied power. The results indicate, and consistently, that the evaporation rate increases with the applied power then peaks before declining. In order to gain insight into these results, we used thermographic infra red imaging to map the temperature field on the external wall of the microchannel. The measurements show that there is a good correlation between the maximum in the evaporative rate and the onset of instabilities of the interface. These instabilities, to our mind, are induced by an increasing temperature gradient along the microchannel wall around the three phase contact line region. These instabilities are revealed by a high speed camera used to record the behaviour of the interface during evaporation.