The dissolution process of the carbonate-rich phosphate rocks from the Kasrik area (Mardin-Mazidagi, Turkey) using dilute acetic acid has been investigated. The work involve to study the effect of the important variables such as reaction time, stirring speed, acetic acid concentration, temperature, particle size fraction, and stoichiometry. It has been found that the P2O5 content of the phosphate rock increases from 12.7 to about 29 wt.% following the dissolution. A mathematical model in the following form was applied to express the dissolution of calcareous material in the rock; -log(1 - X) = kt(m). The dissolution of calcareous material in the phosphate rock has been observed to take place in two steps, the first being fast and the second being slow. (c) 2006 Elsevier B.V. All rights reserved.