Field experiments were conducted in two successive seasons, at the Agricultural Research Center, Giza, Egypt. The aim was to investigate the effect of N-fertilization rate (95.2 and 142.8 kg of N/ha, applied as ammonium nitrate containing 33.5% N in two equal doses at 6 and 8 weeks after sowing), together with foliar application of potassium (applied as potassium sulfate containing 48% K2O at 0.0, 400, 800 or 1200 ppm K2O, applied twice: 70 and 95 days after sowing) and the plant growth retardant (PGR) Pix (applied twice: 75 days after sowing at 0.0 or 50 ppm and 90 days after sowing at 0.0 and 25 ppm) on seed, protein and oil yields and oil properties of Egyptian cotton cultivar "Giza 86 (Gossypium barbadense). The higher N-rate, as well as the application of potassium at different concentrations and plant growth retardant Pix resulted in an increase in cottonseed yield/ha, seed index, seed protein content, oil and protein yield/ha, seed oil refractive index, unsaponifiable matter and total unsaturated fatty acids (oleic and linoleic). Those treatments decreased, though oil acid value, saponification value and total saturated fatty acids. The seed oil content tended to decrease when the high N-rate was applied, but tended to increase with the application of potassium at different concentrations and Pix. There were some differences between potassium concentrations regarding their effects on the studied characters.