Monohydric alcohols with varying chain lengths and isomeric structures, which had significant effects on improving the magnesite and dolomite flotation, were added separately to replace part of dodecylamine (DDA). The intensified effects of alcohols differ with different chain lengths and isomeric structures. Alcohols can enhance the adsorption of DDA and reduce the adsorption distance of DDA on both surfaces of magnesite and dolomite. And the adsorption energy of the mixed collector decreased with the increasing chain length of alcohol. The isomeric alcohols presented more significant effects on lowering the adsorption energy of the collectors. The co-adsorption of alcohol compressed the hydration layer and dilute the water concentration in the hydration layer. Changes of the hydration layer were greater with adding alcohol with a long carbon chain and isomeric structure. Thus, alcohols with long chain lengths and isomeric structures performed better in improving the flotation of magnesite and dolomite. (C) 2020 Elsevier B.V. All rights reserved.