Small angle neutron scattering and adsorption experiments have been performed on a series of humic coals from the Ruhr Basin, Germany. The coals represent the range of rank (0.76-2.23% vitrinite reflectance) within the basin and nearly the complete rank range of bituminous coals. The experiments were carried out in order to get information about changes of the meso- and macroporous structure within the coals as related to rank. Results indicate that the structural parameter of the molecular component of the coals are displaying an exponential behaviour with rank, which is in excellent agreement with the loss of functional oxygen groups. (C) 2004 Elsevier Ltd. All rights reserved.