This study aimed to explore the effect of sodium bicarbonate (0–200 mM) on the production of β-carotene and lipid content in Dunaliella salina and Dunaliella bardawil. Total carotenoid and chlorophyll content were determined at regular intervals by a UV–VIS spectrophotometer. The β-carotene and lipid contents were analyzed using high-performance liquid chromatography (HPLC) and gas chromatography coupled with mass spectrometry (GC-MS). The HPLC results revealed a twofold increase of β-carotene in D. salina and D. bardawil cultures grown with sodium bicarbonate. Moreover, total fatty acid profiles from GC-MS indicated a maximum relative percentage of saturated fatty acids (tetradecanoic acid, 10,13-diethyl, methyl ester and methyl 16-methyl-heptadecanoate) compared to polyunsaturated fatty acids in both algae. Our results indicate that the optimum concentration of bicarbonate (100 to 150 mM) was required to stimulate a positive effect on β-carotene production as well as the lipid profile in Dunaliella sp. © 2015, Springer Science+Business Media New York.