The differential-thermal and thermogravimetric analysis of eight derivatives of 1,4-bis-(5'-hydroxy-7'-sulpho-2'naphthyl).benzenediamide showed that these compounds have a marked exothermic effect, with maxima in the temperature range 280-330~ The derivative of 4-nitroaniline-2-sulphonic acid were found to undergo a blast-like decomposition in the temperature intervals 255-265 ~ and 285-290 ~ which is reflected by large steps in their TG curves.The thermal analysis of disazo pigments permits determination of their applicability at higher temperatures.This work analyses the processes occurring during the thermal decomposition of disazo pigments, derivatives of 1,4-bis-(5'-hydroxy-7'-sulpho-2'naphthyl)-benzenediamide, with the following general structural formula: