The reactive liquid infiltration (RLI) technique, applied to-the MgB2 material, has allowed us to obtain either bulk or wire samples of good transport properties. The evaluation of the voltage-current characteristics, V-I-n, for typical samples, measured by transport at temperatures between 4.2 and 30 K, is presented. The behaviour of the n exponent is discussed in terms of a simple model and the differences between bulk and wire samples are outlined. (C) 2003 Elsevier B.V. All rights reserved.