Abstract The conveyor belts are applied for transportation of a wide spectrum of materials with various technical parameters. An influence of these parameters determines durability as well as damage level of the conveyor belt. The temperature of transported material is one of the relevant criteria with a significant impact on the damaging process of the conveyor belt. An increased degradation of the conveyor belt construction can be caused due to a heat influence. In this article there are analysed several selected samples of the conveyor belt, which was used for transport of a roasted ore with the temperature 120°C. The small failures occurred initially during a current operation of this conveyor belt and these failures led consequently to the development of severe cracks after a longer operational time. Application of a non-destructive diagnostic method enables to consider a next operation possibility of the belt as well as to obtain more detailed information about this type of damaging process.