Thymus capitatus Hoff. et Link. essential oil was constituted by thymol (89.06%) as a major component followed by p-cimene (5.04%) and γ-terpinene (3.19%) after analysis by gas chromatography-flame ionization detection and gas chromatography-mass spectrometry. The antioxidant activity assays of the essential oil used in the inhibition of the radical cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) and the free radical 2,2-diphenyl-1-picrylhydrazyl showed high 50% inhibitory concentration values of 1.24 ± 0.05 mg/L and 0.59 ± 0.02 mg/L, respectively. The essential oil of T. capitatus was tested for antimicrobial activity against Gram-positive bacteria (Salmonella analum, Listeria monocytogenes), Gram-negative bacteria (Escherchia coli, Klebsiella pneumoniae), fungi (Mucor ramamnianus, Aspergillus ochraceus), and yeast species (Saccharomyces cerevisiae, Candida albicans) using the agar well diffusion method. It seemed that L. monocytogenes, E. coli, and K. pneumoniae bacteria were inhibited by the essential oil tested. A strong activity was also observed against fungi and yeasts.