In this paper, we investigate the multi-user per-formance in a two-dimensional (2-D) spreading or-thogonal frequency coded division multiplexing (OFCDM) communication system over frequency and time selective fading channels. To compromise be-tween diversity gain and multiple access interference (MAI), we propose an adaptive fuzzy inference sys-tem to infer adequate 2-D spreading factors and to assign the orthogonal variable spreading factor (OVSF) codes to active users for OFCDM mobile communication systems. Simulation results show that the proposed fuzzy-based code allocation (FBCA) scheme not only suppresses the MAIs induced by non-orthogonality but also exploit the diversity gain over time and frequency selective fading channels and then outperforms the orthogonal code allocation (OCA) scheme at all system loads.