The mobility and bioavailability, and hence, potential toxicity of a trace element in the soil depends on its concentration in soil solution, the nature of its association with other soluble ionic species, and the soil's ability to release the trace element from the soil solid phase. A study was conducted to investigate the chemical speciation of added Cd and Pb and their availability as influenced by fresh Organic Matter (OM) and NaCl in three agricultural soils. The soils were treated with 20 mg Cd/kg as Cd(NO3)2.4H2O, 150 mg Pb/kg as Pb(NO3)2, 20 g/kg alfalfa powder, and 50 mmol/kg of NaCl, and then incubated for 3 months at 60% water holding capacity (60% WHC) and constant temperature (25oC). subsamples were taken after 1, 3, 6, and 12 weeks of incubation and electrical conductivity (EC), pH, dissolved organic carbon (DOC), and concentrations of cations and anions were determined in the 1:2.5 soil/water extract and available Cd and Pb determined in 0.05 M EDTA, extract . Concentrations of organic and inorganic species of Cd and Pb in soil solution were also predicted using MINTEQA2 speciation program. Applied Pb and Cd raised the soluble Pb and Cd in the acid soil and to some extent in the neutral soil but not in the calcareous soil indicating that these heavy metals are not well buffered by the solid phase in soils with lower pH. The most prevalent species of dissolved Pb and Cd in the soils were Pb-DOM and Cd2+ species, respectively. Distribution of dissolved Cd species in all soils did not change with Cd treatment and incubation time, while that of Pb was affected in the acid and neutral soils. Salinity application increased the available and soluble Cd significantly in all soils especially in the acid soil. It, however, had little effect on soluble Pb and no effect on available Pb. Organic matter application decreased availability of added Pb significantly in all soils. On contrary, it raised soluble Pb in all soils except the acid one and converged gradually to the added Pb with time. Influence of OM on available Cd was somewhat similar to that of Pb.