Studies on the reaction pathways involved in the curing of novolac resins with hexamethylenetetramine (HMTA) have been further extended by a C-13 n.m.r. examination of the thermal decomposition of tris(2-hydroxy-3,5-dimethylbenzyl)amine and its reactions with 2,4- and 2,6-xylenol. Both the thermal decomposition and reactions with the xylenols lead to methylene-bridged phenolic structures (for chain extension and crosslinking in curing novolac resins). Other pathways lead to minor amounts of products, and some of which remain in the systems up to 205 degrees C. The results taken in conjunction with our previous studies allow us to draw general conclusions on the overall novolac/HMTA reactions as deduced from the model studies.