Environmental factors, growth phase and microalgal strain have been reported to influence the chemical composition of microalgae. Salinity is one of the important culture conditions that can influence growth and proximate composition of microalgae. Dunaliella sp. is a commercial microalgae species that has been widely used in various sectors due to its biochemical composition. It is also well known to tolerate a wide range of salinity. In the present study, effect of different salinities (10, 30 and 50 ppt) on the growth and proximate composition of Dunaliella sp. at different growth phases were evaluated. Results showed that growth of Dunaliella sp. was significantly higher (p < 0.05) and faster at 10 ppt compared to 30 and 50 ppt. Protein, lipid and carbohydrate content were also higher at 10 ppt. Significantly higher (p <0.05) protein content was observed in stationary phase (10 ppt). In addition, carbohydrate content was also significantly higher (p < 0.05) in stationary phase for 10 ppt. However, higher lipid content was recorded in exponential phase (10 ppt) compared to other phases and salinities. The findings of this study can be manipulated for high biomass production of Dunaliella sp. for commercial use. (C) 2017 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.