The adsorption of O,O-dibutyidithiophosphate and 2-mercaptobenzothiazole on the surface of ZnS has been studied by using the attenuated total reflection (ATR) technique. By utilizing polarized infrared radiation, we got qualitative information about the orientation of the adsorbed collectors. The difference between the absorbance of the s-polarized light and the absorbance of p-polarized light was used to draw conclusions about the orientation. The influence on the orientation of 0,O-dibutyldithiophosphate and 2-mercaptobenzothiazole when adsorbing from a mixture of the two collectors is also reported, as well as the influence of these collectors on the hydrophobicity of the ZnS surface obtained by contact angle measurements.