A cationic polymer, polydiallyldimethylammonium chloride (polyDADMAC), and an anionic (hydrolyzed) polyacrylamide (PAM), were used in sequence to treat the mature fine tailings (MFT) from the oil sands operations in Alberta, Canada. Capillary suction time (CST), specific resistance to filtration (SRF), and filter cake solid content were measured, and cryogenic scanning electron microscopic (cryo-SEM) images of the MFT were taken, before and after the dual polymer treatment to evaluate the dewaterability of the MFT. The results were compared with treatment by a single polymer, which demonstrated that the dual polymer treatment resulted in improved dewaterability of the MFT due to the larger pore sizes.