Abstract: Background and Objective: Essential oil (EO) of M. officinalis L. used in different pharmaceutical and food industries. Salinity (SAL) stress has harmful effects on growth and EO yield. This study aimed to increase the EO composition of M. officinalis L. through the use of Citric Acid (CA) under SAL stress conditions. Materials and Methods: Plants were subjected to different levels of saline soil: 0.0, 1.6, 3.1 and 6.3 dSm–1 with or without CA. The experimental design followed a complete random block design. The averages of data were statistically analyzed using two-way analysis of variance (ANOVA). Results: The highest Fresh Mass (FM) and Dry Mass (DM) were recorded under 0.0 (SAL)×CA treatment with the values of 1776.3, 1540.2 and 300.0 g Pot–1 of two successive seasons. EO contents were increased with CA or salinity×CA. 1.6 dSm–1 (salinity)×CA treatment resulted in the highest amounts of EO with the values of 0.7 and 0.6 g Plant–1 or 2.1-1.8 g Pot–1 during the 1st and 2nd seasons. The highest amounts of major constituents (citral, geranyl acetate and caryophyllene oxide) were obtained from 6.3 dSm–1 (SAL)×CA treatment with the values of 63.7, 11.6 and 9.2%. SAL treatment with or without CA were mostly caused highly significant p<0.001 changes in different chemical classes of M. officinalis L. EO. Conclusion: It was concluded that SAL×CA resulted in significant variation in FM, DM and EO composition of M. officinalis L.