In the present research, synthesis of new 2-(3-chlorobenzyl)-1H-benzimidazole derivatives bearing N-benzylidene, 1,2,4-triazole and N-acylhydrazone moiety is investigated. These novel compounds have been tested for their antimicrobial effects against two of Gram-positive bacterial strains, namely Bacillus subtilis and Staphylococcus epidermidis, and four Gram-negative bacterial strains which were Enterobactercloaceae, Klebsiellapneumonie, Proteus vulgaris, and Salmonella typhymirium. According to their MIC values, which reflect their activity on the bacteria, were classified in three grops: best, good and moderate. So, the best MIC values were obtained 6a and 66. On the other hand, the acidity values of pKa for 6a-d derivatives were calculated with MOPAC 2012 computer program using physico-chemical semi-empirical methods (AM1, MNDO, MNDOD, PM3, PM6, PM6-DH2, PMT and RM1) in water, ethyl alcohol, methyl alcohol, n-propyl alcohol, isopropyl akcohol, n-butyl alcohol, tert-butyl alcohol, ethylene glycol, N,N-dimethyl formamide, N,N-dimetyl sulfoxide and acetonitrile at 25 degrees C.