AbstractActivated carbon appended with organic groups was obtained by a grafting technique using a one-step reaction with diazonium salts. Using the organic aryl amines of 4-bromo aniline and 4-aminoantipyrine as precursors for the corresponding functional diazonium reagents, the bromobenzene and antipyrine molecules were bonded to the surface of carbon. The modified activated carbon was characterized by Fourier transform infrared spectroscopy, X-ray and photoelectron spectroscopy, and BET methods. The results provided evidence of covalent grafting of the organic groups onto the activated carbon by aryldiazonium cations. The present method may provide a convenient and efficient procedure for the preparation of various functionalized activated carbons by means of a single step process.