The surface properties and gel forming propensity of biwetted ultrafine solids (BUS) derived from Athabasca fine tails were studied. The hydrophobic nature of the organic matter associated with the surfaces of these biwetted solids is believed to be responsible for the observed accelerating effect of the BUS on gelation. Our results indicate that prevention or reduction of the amount of BUS entering the tailings pond could have a beneficial effect with respect to fine tails formation. It is also apparent from these results that any structural model, proposed to explain gelation should take into account the attractive forces due to the presence of organic matter.