Understanding contaminant evolution from landfill soils is important in several in-situ remediation processes as well as in thermal treatment and incineration of contaminated top soils. To delineate the rate-limiting processes in the absence of interparticle effects, single surrogate soil particles are examined in this work. The adsorption-desorption characteristics of toluene and carbon tetrachloride on single, surrogate soil particles have been studied using an electrodynamic balance (EDB) under ambient conditions (P = latm; T = 298K). The EDB offers high mass sensitivity (DELTA-m approximately 10(-9)g) in the absence of external mass transfer limitations and interparticle effects. In this work, three types of solid particles, 100-170-mu-m in diameter, were examined, namely montmorillonite, a clay, and two synthetic chars, Spherocarb and Carbopack, of very different pore structures. Three different values of relative pressures, P/P(o), were tested for each liquid by changing the saturator bath temperatures. Significant differences were identified among the various solid-organic compound pairs examined in adsorption-desorption sequences in the EDB. These are strongly correlated with differences in the solid pore structures.