New oligomeric amides were synthesized by the reaction of m-xylylenediamine and dimethyl oxalate to investigate the average molecular weight dependence of the protonic conductivity. The average molecular weight was determined by the analysis of the Matrix Assisted Laser Desorption / Ionization Time of Flight (MALDI-TOF) mass spectra. The average molecular weight was decreased with increasing the quantity of water in the reaction condition. Some end groups of the oligomers were hydrolysed from the methoxycarbonyl groups to the calboxylic acid groups. The oligomers with the different average molecular weight exhibited different relative humidity (RH) dependence of the protonic conductivity. The protonic conductivity depends on the average molecular weight at the RH of 95%. The difference between the maximum and minimum protonic condcutivity is about three orders of the magnitude. The activation energy for the protonic conduction in one of the oligomers is 0.66 eV. (c) 2008 Elsevier B.V. All rights reserved.