Abstract A theoretical model for the magnetic field dependence of the transport critical current density in granular superconductors ( J c( B)) is proposed. In this model the transport critical current density is controlled by the weak-links (WLs) network present in the samples, and also, the influence of the field penetrating the grains is considered. Our results depend on the microstructure via the parameters of the WL distribution, and seems to reproduce the overall experimental data reported in the literature. A characteristic field is found from our study that characterizes the J c( B) dependence. Different field regimes are considered leading to simple expressions for J c( B).