ABSTRACT: Selection of the suitable pretreating solutions to be used prior to clay mineral analysis for Eocene flysoh deposits formed in the Osmaniye - Aslantaş dam area Is discussed. Various solutions of different concentrations, such as NaOH, GH3-GQONa, HCI and 2 SO4 are used for determination of particle size analysis, and of clay minerals-without destroying their structure - aloung with analysis of some extracta`ble elements İn flysoh and similar sedimentary rocks. As result, the most suitable pretreatlng solution to be used as dispersant rs 0.1 M H2 SO4 The most suitable solu , tions for elemente! extraction of Ca++, Mg+ ` and Na+ and K+ are 0.5 M H2 SO4 respectively. The most suitable pretreatlng solutions for clay mineral determination are In the orderof 0.5 M NaOH and 0.1 M HCI.