We have carried out synthesis of azo dyes of 4-(1,3-benzoxazol-2-yl) aniline (2a-j) in the presence of green and cost effective catalyst K10-Montmorillonite clay, using substituted phenols as coupling agents. The azo dyes were obtained in good isolated yield. The synthesized azo dyes have been evaluated in vitro for their antimicrobial activity against S. aureus and E. coli as bacterial strain and A. niger fungal strain. Some of the compounds displayed pronounced biological activity. The resulting compounds were characterized by IR, 1H NMR, 13CNMR and Mass spectroscopic analysis.