Hydrophobicity-hydrophilicity balance relationships for self-induced and sodium sulfide-induced flotations of sulphide minerals have been established, through solvent extraction-chemical analysis of neutral sulphur (S°) on the surfaces, measurement of redox potential (Ept) of flotation pulp, and flotation tests. They may be’indicated as [S°]/[OH−] and [S°]/([OH−]+[HS−]), respectively. The neutral suphur (S°) was considered to be responsible for the hydrophobicity, the amount ([S°]) of which was controlled byEpt. The critical value of [S°] was proposed as a new concept. The hydrophilicity was contributed to OH− ion for the self-induced flotation, and to both HS− and OH− ions for the Na2S-induced flotation. At a given pH value, hydrophobicity and floatability increase with [S°]. For different pH values, a higher pH value results in stronger hydrophilicity, and hence the hydrophobicity and flotation require more [S°]. Lower pH values are in correspondence with the smaller [S°].