Trona ore located in Beypazari is extracted by solution mining method with well pair connected by directional drilling technology. This thesis covers the determination of the dimensions of the initial (vertical) caverns formed in underground by use of a computer modeling (trademark: WinUbro/Poland) on the basis of horizontal and vertical leaching rates. The leaching rates were determined using the trona core samples from the ore deposit. The effect of insoluble content and the thickness of trona layer and solvent temperature on the initial cavern dimension were studied. The outcome of this study showed that the better the trona layer quality from the point of view of thickness and insoluble content, the wider the vertical cavern size is. In 1 m thick trona layer with 20% insolubles, it is possible to develop caverns of 6 m width, which is the minimum size for well pair connection. On the other hand, it is determined that the effective leaching time depends mainly on solvent temperature.