Abstract: Detailed research on the quality of the reservoir for oil research and production is very important to reducecosts because of the high cost of oil exploration and evaluation. The aim of this study is to determine petroleumreservoir rock quality of the Mollaresul formation which is composed of Jurassic-Lower Cretaceous aged limestoneswithin the Haymana-Polatlı basin. The reservoir quality of the limestones was determined by standard field studiesand laboratory analyzes, porosity-permeability analyzes and petrographic studies. In the field studies, the formationis observed as massive and stratified, and it is deposited from a shallow to deeper marine environment. According toporosity-permeability analyses, the porosity values of the formation are between 30% and 45%, and the permeabilityvalues are between 5.2 and 7.7 md. Layered, abundant cracked and karstic cavities of the formation formed a goodporosity in the formation. Although fractures and cracks in the formation greatly increased porosity, secondarycalcite, ferrous (Fe) and manganese (Mn) cement filling the fractures and cracks did not make the permeabilityas high as the porosity. In conclusion, according to the field and laboratory studies, Mollaresul formation shows amoderate reservoir rock quality.