A synthesis of new (E)-6-substituted-3-((4-substitutedphenyl) diazenyl)-2,4-dimethyl quinolines has been achieved by the Combs reaction. The synthesis of the derivatives is based on diazonium coupling reaction. The intermediate compound (E)-3-((4-substitutedphenyl)diazenylpentane-2,4-dione derivatives (I-VI) was obtained from diazonium coupling reaction between primary aromatic amines with acetyl acetone, then condensation to a (Z)-3-((E)-(4-substituted phenyl)diazenyl)-4-((4-substituted phenyl)imino)pentan-2-one derivatives (VII – XIV) followed by elimination of a water molecule and cyclisation of the result by the heating and elimination of water in presence Sulphuric acid to afford final compounds (E)-6-substituted-3-((4-substitutedphenyl)diazenyl)-2,4-dimethylquinoline derivatives (XV – XXII) The identities and purity of synthesized compounds were elucidated through the thin layer chromatography (TLC), melting point and spectroscopy data such as (IR, UV, 1HNMR, and mass spectroscopy).