Purpose of this work was to study the resistance to supraoptimal temperatures of various maize hybrids by evaluating some changes in seed germination and mobilization of reserve substances.  Introduction. The initial stages of plant growth is the more influenced by abiotic factors, in special by high temperatures. Supraoptimal temperatures delay seed germination and redu-ce the growth rate of embryonic roots and shoots. [5]. Taking into account that the number of studies on germination characteristics and mobilization of reserve substances of maize seeds in correlation with their tolerance to non-optimal temperature is very limited, research on the primary resistance to supraoptimal temperatures of maize lines used in the Republic was initi-ated [3].