Background and Aim: Sonneratia apetala plant has been used in traditional medicine in south Asian countries for treating diarrhea, hepatitis, inflammation, wounds and ulcers. The leaf extract of this plant has shown promising antibacterial activity and it is essential to isolate that antibacterial compound in pure form. Materials and Methods: In this study, a bioassay-guided isolation and characterization approach was taken to isolate and characterize the antibacterial compound from the S. apetala Buch. Ham leaf. Petroleum ether, acetone and water extracts were prepared and tested against eight human pathogenic bacteria. Water and acetone extracts have shown the inhibition of bacteria but the more promising acetone extract was carried forward for further study. The compound was isolated using the preparative column chromatography method. The isolated compound was studied for antibacterial activity using TLC-bioautography. Further characterization was done using the UV-Vis spectroscopy and FT-IR spectroscopy. Results: The findings of the present study showed the presence of various valuable phytochemical constituents. Conclusion: The presence of an antibacterial compound highlights the importance of this plant as a source of phytochemicals with medicinal properties.  This study indicated that the geographical location of the plant is one of the factors which determines the antibacterial potency of the leaf extract.