The aim of the present work is to investigate the effect of a prolonged leaching test (more than a year) on the microstructure of solidified cementitious wasteforms. A set of four different cement-based monoliths (Ap, Bp, Cp and Dp) was prepared, and for each series an uncontaminated sample was prepared as reference (A-D). An organoclay was added in all pastes as pre-sorbent material for the pollutant; a model liquid organic pollutant, 2-chloroaniline (2-CA), was added only in the contaminated ones and different types of admixtures, chosen among those typically employed in the concrete mix-design, were used. After the first 28 days of curing, all the monoliths, contaminated and uncontaminated, underwent a dynamic leach testing (DLT) for more than 1 year in deionized water. (C) 2009 Elsevier B.V. All rights reserved.