The changes induced by urea - modification which appears on the surface of activated carbon were measured by attenuated total reflectance (ATR) Infrared (IR) spectroscopy and Raman spectroscopy, elemental analysis, gas adsorption analysis, selective titration, pH of the carbon surface. It is important to know the nature of surface functional groups of nitrogen-modified activated carbon in order to understand their chemical and catalytic properties. The activated carbon samples were obtained by a physico-chemical method using steam activation. After activation the samples were treated with urea aqueous solution and heated from 400°C up to 800°C in nitrogen atmosphere. The IR and Raman spectra were measured after heating. Especially, in the high temperature region over 600°C, the intensity of the band corresponding to the C-H aromatic bond decreased. At least, two types of hydroxyl groups (phenol and alcohol groups) were obtained in carbon samples. The peak of phenol and/or alcohol O-H groups was reduced with treatment temperature. The catalytic activity of the initial and modified activated carbon samples were analyzed by the chemiluminescence technique. Thus, these changes influence the catalytic activity of the activated carbon in heterogeneous systems.