Microalgae are a potential source of biodiesel. Isolates of the present study were isolated from Wadi-henifa, Rhiyad, Saudi Arabia. The urgent need for an alternative and sustainable energy has created renewed interest to analyse the microalgae for biodiesel production. The greatest lipid content reached 20.2, 16.4, 9.7 and 12.3 % under the optimal conditions of nitrate concentration (0.75 g/l), temperature (24 and 30 °C), salinity (0.05 and 0.001 mole/l) and pH (8 with Chlorellavulgarus and 9 with other strains), Chlorella vulgarusArthrospiraplatensisGomont and Spirulina major, respectively. It was demonstrated that the obtained model was effective for predicting lipid productivity of the isolated microalgae. The maximum protein content was at 24°C for Chlorella vulgarus,ArthrospiraplatensisGomont and Spirulinamajorkütz, (53, 56.8 and 54 % respectively), while the maximum protein content ofArthrospira maxima was at 30°C (56.2 %).The optimum protein content was found at pH9forArthrospiraplatensisGomont , Spirulina major kützandArthrospira maxima(48.47, 55.47 and 63.25 % respectively) while in case of Chlorella vulgaruswas at pH 8 (51 %).The maximum protein content was 76.96 % at 0.001 moleNacl/L, 54, 75.38 and 75.09 % at 0.05 mole/L for Chlorella vulgarus,Spirulina major kütz, Arthrospira maxima andArthrospiraplatensisGomont respectively. Results of this study revealed thatthe mention optimization conditions enhanced protein content of the tested isolates. ArthrospiraplatensisGomont, SpirulinamajorkützandArthrospira maxima are promising organisms with high nutritional value for animal and human beings.