The specific role of filler-rubber interactions in dynamic properties was investigated. Natural rubber compounds, filled with N330 carbon black, were used, and the filler surface was modified through a gas treatment in the solid phase. The effects of this filler surface treatment on the dynamic properties were systematically studied at equal filler dispersion levels. The dynamic properties were assessed for both uncured and vulcanized compounds, and a number of advanced investigative techniques were used to characterize not only the modification of the carbon particle surface by an oxidative treatment but also the structure of the filled rubber compounds. Particular attention was paid to techniques that gave access to the segmental mobility to explain the benefit observed with modified carbon black. A molecular interpretation, based on NMR measurements, was considered that took into account physicochemical parameters. (C) 2003 Wiley Periodicals, Inc.