The main objective of this project was blending of aniline and toluene with local reformat gasoline, to enhance the octane number of reformat gasoline product from Khartoum refinery (Sudan). Reformat gasoline was tested according to American society for testing and materials(ASTM), Tests included distillation, sulfur content, density, vapor pressure, oxidation stability, cupper strip corrosion, gum existence, lead content, and octane number determination by Cooperative Fuels Research )CFR engine(. Previously tetra ethyl lead (TEL) and tetra methyl lead (TML) have been used to improve the fuels octane number, but they have negative effects on the environment, and have been banned internationally. The motor octane number (MON) of reformat gasoline used in this research was recorded (88.5) before additives. In order to enhance the ON of reformat gasoline, aniline and toluene were added to the reformat gasoline with different concentration (5, 10,% v/v). Octane number of blends was measured by CFR engine. The properties of reformat gasoline after all additions were improved to the limits assigned by ASTM and Khartoum refinery. Motor octane number (MON) was increased into the range of 1 - 7. Addition of 10% v/v aniline showed high value of MON, but addition of 5% v/v toluene showed lower value of MON.