A pilot study of the petrified forests of Lesvos Island and of Kastoria and the application of a nondestructive method for the identification and measurement of soluble salts contained into material fount on both sites are presented here. This method is based on the application of neutral paper pulps impregnated in deionized water on some trunks. The study includes monitoring of environmental conditions, macroscopic examination and mineralogical study of fossils. Based on climatological data, the period where frost action and temperature variations take place was determined. The results indicate that in Lesvos Island there is an extensive problem of deterioration due both the crystallisation of soluble salts and the frost action during the winter. In Kastoria there are problems, deterioration caused by the frost action, during the months December to February, the crystallisation of soluble salts and biological depositions.