The substructure development in f.c.c. monocrystals and polycrystal grains under cold rolling is modelled with the help of evolution equations for the densities of redundant cell wall and non-redundant fragment boundary dislocations as well as of mobile and immobile disclinations in six cell wall and fragment boundary families. The slip rates for the I? f.c.c. slip systems are calculated by a full constraints Taylor algorithm. The critical resolved shear stresses are derived from the dislocation and disclination densities. Substructure and crystal orientation are updated alternately in each integration step. The model is able to predict cell wall and fragment boundary spacings as well as misorientations in reasonable agreement with experimental data obtained in TEM studies on aluminium. The subset of preferably splitting grains in a polycrystal is found in reasonable agreement with OIM results. (C) 2001 All Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.