The objective of the present work was the synthesis of 2- (2, 3, 4, and 5 substituted phenyl) 3-hydroxy-4H-Chromen-4-one and evaluation of in-vitro antimicrobial activity. Based on this a new series of compound had been planned to synthesize by reacting 2-hydroxy acetophenone and various aromatic aldehydes in the presence of potassium hydroxide, methanol and 30% hydrogen peroxide. The synthesized compounds were characterized by IR, NMR, and Mass spectroscopy. The in-vitro antimicrobial profile of newly synthesized compounds were carried out by using agar diffusion method using bacterial cultures of Staphylococcus aureus (ATCC 9144) and Escherichia coli (ATCC 25922) and fungal culture of Aspergillus niger (ATCC 9029). By observing it was found that most of the synthesized compounds executed moderate to good antimicrobial activity against the tested micro-organisms. The most of the synthesized compounds were active against all the tested micro-organisms for antimicrobial activity with an MIC range of 15-40µg/ml. The MIC values for the synthesized compounds were found to be 4B (MIC of 15 µg / ml), 4J(MIC of 16 µg / ml), and 4E (MIC of 17) against Staphylococcus aureus (ATCC 9144) and 4B (MIC of 16 µg / ml), 4J (MIC of 19 µg / ml), and 4E (MIC of 18) against Escherichia coli (ATCC 25922) and 4A (MIC of 16 µg / ml), 4C (MIC of 19 µg / ml), and 4E MIC of 18 µg / ml) against Aspergillus niger (ATCC9029).
