A comprehensive DTA study is reported of eight methyl-phenols, 4-methoxy-phenol and four methyl-halo-phenols and of the corresponding p-nitrobenzoylchloride, 3,5-dinitrobenzoylehloride and p-phenylazobenzoylchloride derivatives, prepared 'in situ' by heating intimate mixtures of phenol and acid chloride in a DTA system. The thermal analysis data, in particular, the derivative formation temperatures, are interpreted in terms of the inductive, mesomeric and steric effects associated with the ring substituents of the phenol and acid chloride and the extent of inter- and intramolecular hydrogen-bonding existing in these systems. The DTA data collectively, provide a comprehensive data base for the identification and characterisation of these phenols via DTA. A DSC study by Crandall and Pennington [1] of phenol, resorcinol and eugenol and of the corresponding p-nitrophenylben zoate derivatives, suggested that phenols in the solid state can be charaeterised via 'in-situ' derivative formation in a thermal analysis system. This postulate was extensively tested and reported as Part 1 of a detailed DTA study [2] of phenols a series of haio-phenols were eharaeterised via a DTA study of the individual phenols together with the 'in-situ' formation of the corresponding p-nitrobenzoylch loride (p-NBC), 3,5-dinitrobenzoylchloride (3,5-dNBC) andp-phenylazobe nzoylehloride (p-PABC) derivatives. The second part of this comprehensive study is reported here as a DTA study of eight methyl-phenols, 4-methoxy-phenol and four methyl-halophenols and of the corresponding p-NBC, 3,5-dNBC and p-PABC derivatives. The thermal analysis data, and in particular, the derivative formation