The effects of suspension pH, concentration of surfactant (cetyltrimethylammonium bromide, CTAB) and concentrations of electrolytes (FeCl3, CaCl2 and NaCl) on the recovery of agglomerate and on the reductions in ash and pyritic sulfur in selective oil agglomeration were investigated. The correlation between recovery and reductions in ash and pyritic sulfur and the zeta potential of the agglomerates was also studied. It was found that there was a close correspondence between them and that zeta potential measurements on the agglomerates would give a measure of the effectiveness of oil agglomeration.