The melting process of unstable pesticides such as methomyl, atrazine, lenacil, captan, daminozide and dodine has been investigated
by DSC. The influence of the heating rate on the melting enthalpy, melting temperature and cryometric determination of purity
was studied. The mean rate of thermal decomposition at the melting temperature was introduced to compare the stability of
the examined pesticides. The investigated pesticides may be classified into two groups. In the first group the determination
of purity is independent of heating rates and in the second one the purity is dependent on the heating rates.