In this work, the electroflotation of cassiterite fine ranges using Rhodococcus opacus (R. opacus) as bioreagent has been carried out. The interaction between R. opacus and mineral surface was valued through the zeta potential, contact angles measurements and adsorption studies. Furthermore, studies were attempted to check the effect of current density and microorganism concentration on mean bubble size (Sauter). After the interaction, the resulting particles exhibited hydrophobic characters, as verified by the increase of the contact angle. Also, the electrophoretic mobilities of cassiterite particles showed a mean value close to zero after interaction with R. opacus. The measurement of bubble size by laser diffraction showed a mean bubble size of 26μm. Current density and bacterial concentration seem to be the main parameters affecting the mean diameter of the bubbles. An electroflotation test reported recovery of around 64.5% at pH 5, concentration of 2.87x1012 cells/ml (50 mg/L) and current density of 51.4 mA/cm2.