Of the natural food additives, rosemary has been widely accepted as one of the spices with the highest antioxidant activity. Antioxidants are substances which are able to prevent or inhibit oxidation processes in food products. Natural antioxidants have gained considerable interest to replacing synthetic antioxidants. In this study, rosemary leave was selected as a source of natural antioxidant. The rosemary extract contain the components that have anticancer potential like carsol carsonic acid and rosemary acid. The aim of this study was extraction and characterization of food additive of rosemary leaves. A procedure for soxlet extraction followed by sampling and characterization from the leaves of the rosemary was implemented. Eighteen components were identified in the oil of Rosmarinus officinalis by GC-MS. Monoterpene hydrocarbons were found to be the major group of compounds these are α‐pinene (12.08 %) followed by camphor (9.14%). Other predominant components were camphene (2.14 %), β‐pinene (2.45 %), bornyl acetate (6.79 %), limonene (1.98 %), borneol (5.07%), and α‐terpineol (3.08%). The parameters taken up for the study like particle size, drying conditions and solvent type were affect the extraction yield and quality of the rosemary oil. Maximum yield (0.95%) was observed from shade dried rosemary leaves at a particle size of 1.18mm with methanol solvent. The antimicrobial inhibition potential of the extract was also examined by using agar well diffusion method. The inhibition effect of methanol (12.5-17mm) is higher than that ethanol (12.5-15mm) and ethyl acetate (12.4-13.5mm). The rosemary oils antioxidant activity was also examined by DPPH scavenging activity assay and the oil exerted antioxidant scavenging activity. The maximum DPPH radical inhibition activity percentages of rosemary extracts were 76.69%.