A new kind of calorimeter, commercialized by SETARAM SA and operating in isoperibolic mode, appeared 2 years ago: the differential calorimeter DRC(R). This DRC was developed by Aventis Pharma in their own laboratories and has been used as standard tool for 10 years. The Swiss Institute for the promotion of safety and security (Organic Process Research and Development (2002) to be published) has also studied this calorimeter. In order to show the accuracy of this apparatus, we can compare the DRC with the RC1 from Mettler Toledo which is the reference for safety studies. We can demonstrate the exactitude of results in a wide range of reactions: with one step (neutralization) or two steps (aldolisation-crotonisation), semi-batch reactions with addition of one reagent or simultaneous additions of two reagents, slightly or very exothermic reactions. In each situation, DRC will obtain the same data and results in less time with a smaller amount of raw materials. (C) 2003 Elsevier Science Ltd. All rights reserved.