The effect of substituted benzene groups of cationic thermal latent catalysts i.e., N-benzylpyrazinium hexafluoroantimonate (BPH) and N-benzylquinoxalinium hexafluoroantimonate (BQH) on thermal, rheological and mechanical properties of the neat epoxy resin (diglycidyl ether of bisphenol-A, DGEBA) was studied in this work. Latent properties were studied by measuring the conversion as a function of curing temperature using a dynamic DSC analysis. The study of cure reaction, thermal behavior, and rheological properties on the neat epoxy resin initiated by both catalysts was investigated by means of DSC, TGA, and rheometer. And the mechanical properties were also determined by flexural and impact tests. As a result, the presence of the catalysts studied in this system appeared significantly to enhance the thermal properties. All results of thermal, rheological, and mechanical properties of DGEBA/BQH system were superior to those of DGEBA/BPH system. This was probably due to the presence of the bicyclic group which led to the ductile fracture properties, resulting in an increase in the resistance to the deformation and to the crack initiation of the epoxy system.