Recently, amongst the various electrical discharge machining (EDM) processes, the number of micro-EDM applications has been increasing owing to the small reaction forces involved. However, the mechanism of material removal in a single discharge using a dielectric fluid is not yet fully understood. In this study, a low-melting-temperature alloy (melting point:47Celsius), that is expected to generate a larger than usual removal volume for each discharge, is used. Through the observation of the craters generated on the low-melting-temperature alloy under each discharge condition, the mechanism of material removal is investigated. Single-discharge experiments on the low-melting-temperature alloy using tungsten electrodes of 0.1mm diameter, were carried out in kerosene oil or de ionized water. The experimental parameters were electrode polarity, discharge current and pulse duration. From the results of these experiments, the relationships between the removal volume of the discharge crater and the single-discharge conditions are elucidated.