Introduction: This work is an analytical study of Essential Oils (EO) extracted from six medicinal plants. This makes it possible to determine their physicochemical aspects, to calculate the yields of EO and to analyze their phytochemical compositions qualitatively and quantitatively in order to correlate them in new studies with antimicrobial activities. Materials and Methods: Six medicinal plants were selected for our study: Artemisia vulgaris, Ocimum basilicum, Syzygium aromaticum, Thymus vulgaris, Origanum vulgare, and Rosmarinus officinalis. The extraction of the EO was carried out by hydrodistillation using a device of the clevenger type. The yield of EO is the ratio of the mass of the EO to the mass of the plant material used, expressed as a percentage. The physico-chemical characteristics were studied and the qualitative and quantitative analysis of the phytochemical composition was carried out using gas chromatography coupled with mass spectrometry. Results: the yields obtained are very good, the physicochemical characteristics coincide with those described in the literature, the phytochemical composition is very divergent compared to those found by different authors, this is due to several factors such as the chemotype, Harvesting season, extraction technique, extraction equipment and technology, etc. Conclusion: the essential oils studied are very rich in phytochemical substances belonging to different chemical families; this richness is promising of several biological activities, especially antimicrobial.