According to the solution of convective diffusion equation, which defines salt transportation in soils, effectiveness and practical value of calculations depend on hydro-chemical parameters. In this study, mathematical expressions, which enable to find hydro-chemical parameters of salt transportation in soil, were determined based on the solution of convective diffusion equation. In 100 cm depth of saline-sodic soils, hydrochemical dispersion parameter (λ), Peklet parameter (Pe) and soil's salt loss coefficient (α) have been found to be 1.667, 0.6 and 1.024, consecutively. The values of θ(ξ,η) function, which depends on salt concentration of soil before (C0) and after (Sor) washing (C0) and in washing water (Cy), is calculated. And it is possible to determine λ parameter, Ny- the amount of washing water and the amount of soil in layer, which is washed, by using the calculated values that are mentioned above. © 2006 Asian Network for Scientific Information.