Olive cake and bakery wastes are considered as important feed ingredients that are incorporated at different levels in animal diets and can be used in bio-fuel production. Major nutrients of both feed ingredients have been characterized in the literature; however, minerals concentration and extent of variation have been overlooked. The importances of characterization of minerals content and extent of variation between different sources have a significant applications in feed industry and bio-fuel production produced from biomass pyrolysis reactions. The purpose of this study was to investigate minerals composition (Ca, Mg, K, Na, P and S) in olive cake and bakery wastes produced in Jordan and to discuss the results in relation to the average and the extent of variation with tabulated values mostly used in literature. Olive cake and bakery waste samples (twelve samples each) were collected from different olive mills and bakeries distributed in Jordan. Among all analyzed bakery wastes samples, Na had the highest average concentration (0.36%) and ranged from 0.02 to 0.67%, whereas, Mg had the lowest concentration (0.03%) and ranged from 0.01 to 0.05 %. Among all analyzed minerals in bakery wastes, Ca, K and S had the lowest CV% (16.62%, 16.57%, and 16.28%, respectively), whereas, Na had the highest CV% (69.51%). Among all analyzed olive cake samples, this study showed that K had the highest average concentration (0.75%) and ranged from 0.46 to 1.98 %, whereas, Na had the lowest concentration (0.02%) and ranged from 0.01 to 0.03 %. Among all analyzed minerals in olive cake samples, Ca had the lowest CV % (17.48%), whereas, K had the highest CV% (53.41%). It can be concluded from this study that the existed variation in minerals concentrations within the investigated by-products is necessary to recommend minerals supplementation strategies and have applied consequences on optimization bio-fuel production process.