The simultaneous polymerization and crystallization of aniline has been reported earlier. In this article, the X-ray crystal structure analysis, SEM morphological analysis and electrical properties of such crystals of oligo-polyanilines are being reported. The structural analysis shows a pseudo-orthorhombic lattice. The SEM images reveal flaky and triangular growth habit with granular overgrowths on the surface. The bulk conductivities achieved vary from 10(-5) S/cm to 10(-7) S/cm as the oxidant concentration is reduced from 5 to 0.1%. The temperature dependence showed a transition point upto which there is a decrease in current and above which the current increases. The ESR studies reveal polarons involved in charge conduction and their concentration is proportional to the oxidant concentration. The X-ray patterns, conductivities, and ESR results have been correlated with the degree of polymerization results obtained from GPC studies. (c) 2007 Wiley Periodicals, Inc.