Abstract: A device for determining the moisture content of a material which includes a micro wave heating unit (1) for heating a sample of the material which is under investigation and a weighing device (3) for weighing the sample during heating and providing signals representing a series of measurements of the weight of the sample at specific times. The weighing device is connected to a processing unit (4) which is a microprocessor and which includes a computer (9) which produces signals representing the loss of weight of the sample in the course of heating and which computes the parameters of a asymptotic function and which represents the loss of weight of the sample in the course of time. There is also a calculator (11) for determining the differences between two asymptotic values, and a comparator (12) for comparing the differences with a reference value representing the acceptable uncertainty in regard to the moisture content of the material.