The invention pertains to a method for separating uranium and/or thorium from an aqueous suspension, said method comprising: a) Contacting said suspension with at least a polymer having formula (I) wherein n is an integer which is not 0 and is no more than 50 R1 is H or CH 3 , R2 is H or a C1-C20-alkyl, R3 and R4 are independently H or a C1-C20-alkyl, X, Y are O or NH, said polymer being soluble in said aqueous suspension, and wherein when R3 and R4 are H, p is an integer which is 1 or more and 10 at the most, and said polymer is a flocculating polymer, and when at least one of R3 and R4 is not H, p is an integer which is 3 or more and 10 at the most, and said polymer is a thermosensitive polymer and has a LCST in said suspension, b) Carrying out at least one of the following steps b1) and b2) b1) If said suspension contains uranium, separating the aggregates resulting from flocculation of said polymer, from said mixture, b2) If said suspension contains thorium, modifying the mixture until the LCST of the polymer in the mixture is reached or exceeded and separating the resulting aggregates from said mixture; and c) Recovering at least one of uranium and/or thorium-free mixture, aggregates bearing uranium and aggregates bearing thorium.