A formalized classification of Czech thermophilous oak forest vegetation is presented. It is based on the Cocktail algorithm, including the formulation of a set of explicit definitions of vegetation units that are used for unequivocal assignment of relevés to defined vegetation types. Eight out of 10 traditionally distinguished associations of thermophilous oak forests were formally defined: Bohemian warm and dry oak forest (Lathyro versicoloris-Quercetum pubescentis), Moravian warm and dry oak forest (Pruno mahaleb-Quercetum pubescentis), dry-mesic oak forest on basic rocky substrates (Corno-Quercetum), dry-mesic oak forest on acidic substrates (Sorbo torminalis-Quercetum), Moravian dry oak forest on acidic substrates (Genisto pilosae-Quercetum petraeae), dry-mesic oak forest on heavy soils (Potentillo albae-Quercetum), dry-mesic oak forest on sandy soils (Carici fritschii-Quercetum roboris) and dry oak forest on loess (Quercetum pubescenti-roboris). The specific features of Cocktail classifications are discussed. The complementarity of the traditional, imperfectly formalized classifications and modern formalized classifications is stressed.