Two field trials were conducted during the summer seasons of 2009 and 2010 on sweet sorghum at Giza Agricultural Research Station. Agricultural Research Center, Giza Governorate, to study the effect of three treatments of potassium fertilization, viz., 24 and 30 kg K2O/fed as potassium sulfate 48% K2O as a mineral fertilizer, both of them with 2 bags bio-fertilizer (potassium Mag/fed as a recommended dose) and 36 kg K2O/fed without bio-fertilizer on yield/fed and chemical composition of three sweet sorghum varieties, namely, Honey, Brandes and Sorgo. Sweet sorghum varieties differed significantly for stripped stalk, juice and surup yields/fed, TSS, purity and extracted juice% as well as chemical composition, i.e. sucrose% and reducing sugars% in juice and syrup. Sorgo variety was the best as compared to Brandes and Honey. The highest values of the most aforementioned traits were obtained at 30 kg K2O/fed with 2 bags of biofertilizer. The interaction between all studied traits were insignificantly affected in both seasons. Therefore, these results give evidence to the use of sweet sorghum for syrup production instead of sugar cane, to reduce the vast gab between sugar production and consumption.