ABSTRACT Secondary metabolites are natural plant constituents that exhibit various pharmacological activities. According to Ayurveda, the leaves and seeds of many Cassia species are acrid, laxative, antiperiodic, anthelmintic, ophthalmic, liver tonic, and cardiotonic. Additionally, some Cassia species are used as natural pesticides in organic farms. It is, in fact, the responsibility of the scientific community to validate the medicinal properties of these traditional claims through scientific research. In this context, the present study aimed to qualitatively screen the phytochemicals in five selected Cassia species and validate the compounds using Fourier transform infrared spectroscopy (FT-IR). Furthermore, the study sought to analyze the microbicidal potential of these compounds against selected bacterial strains. Five Cassia species (C. tora, C. alata, C. fistula, C. occidentalis, and C. mimosoides) from the family Leguminosae were selected for this purpose. Finely powdered leaves were subjected to hot continuous Soxhlet extraction using solvents ranging from non-polar to polar. Phytochemical screening of the different solvent extracts revealed the presence of various phytochemicals. FT-IR fingerprinting analysis confirmed the presence of alcohols, phenols, alkanes, carboxylic acids, aldehydes, alkenes, nitro compounds, esters, ethers, aliphatic amines, and alkyl halides, validating the presence of diverse phytochemicals in the plants. Additionally, the microbicidal potential of the extracts was observed as inhibition zones on agar plates via the disc diffusion assay. Gram-negative bacteria were found to be more sensitive than Gram-positive ones. From the results it could be concluded that the studied species of Cassia are potent sources of phytochemicals having significant biological activities. Keywords: Cassia, FT-IR, Phytochemicals, Bactericidal, FT-IR Finger printing