A new adiabatic calorimeter ACTRON 5 is described, in which the adiabatic conditions are realized due to change the temperature in the thermostat. For example, it was used to carry out the titration of boric acid with sodium hydroxide and for the kinetic investigation of thiosulfate reaction with hydroperoxide. Relative measurements of beat capacities are also directly possible. At last hazardous reaction can be observed on its way to point of no return.