Benzohydroxamic acid (BHA) has been widely used as the collector for cassiterite flotation, whereas low collecting ability of BHA need to be improved. It is shown through flotation that BHA exhibits weak collecting capacity to cassiterite even in the case of using lead nitrate as the activator, but the superior floatation performances of lead(II)–BHA complexes is observed. The adsorption isotherms of BHA onto cassiterite reveal a higher adsorption density around pH 9 using lead(II)–BHA complexes as the collector. The complexation of lead(II) by BHA has been studied by differential pulse voltammetry. In weak alkaline solution, [Pb(HL)]+ and [Pb(OH)(HL)] species with significantly collecting power are well predominant. Zeta potential studies demonstrate a stronger affinity to the mineral surface of Pb2+/Pb(OH)+–BHA complexes. XPS and FTIR studies indicate that chemisorption with the similar formation of Sn–O–Pb bond is the main interaction between the two kinds of collector and cassiterite.