This study focuses om the changes in viability and chemical composition of maize hybrid SC168 during storage conditions. This study was conducted at the Seed Technology Department, at Sakha Agricultural Research Station, ARC, Egypt during November-2018 to April-2020. Storage conditions were two storage periods 6 and 18 months, four regimes of relative humidity, 46%, 65%, 72% and 80% and three package materials i.e. jute bags, low density polyethylene and hermetic bags. The results revealed that increasing storage period from after harvest to 6 and 18 months led to the increasing in deterioration of the viability and quality of the seeds and caused the highest of electrical conductivity, acidity% and moisture content in the seeds storage. Increasing relative humidity from 46 to 80 % significantly increased the mean value of electrical conductivity of the seed soak water (from 5.12 to 11.41 mS m-1), moisture content and acidity%, and significantly decreased the mean seed germination %, shoot length, root length, seedling dry weight, oil% and crude protein %. Hermetic bags gived high seed germination, seedling vigor and oil % and low seed moisture content, electrical conductivity and acidity %, and therefore they could delay seed quality deterioration compared with low density polyethylene and jute bags and that in conditions of high relative humidity for a period longer than six months. Finally, we can recommend the use of hermetic bags to maintain the vitality and quality of maize seeds under high relative humidity conditions for a period of up to 18 months.