Viscosities of aqueous solutions of La NO3)3, Ce(NO3)3, and Pr(NO3)3, in the concentration range of 0.2 to 1.0 M were measured in the temperature range of 293 to 333 K. Viscosity data obey the equation h = A exp (Eh/RT). Flow activation energies for all the three system were calculated. Various thermodynamics parameters i.e. DH, DS and DG for these systems were also evaluated