N,N,N',N'-tetraoctyl diglycolamide (TODGA) and N,N,N',N'-tetra(2-ethylhexyl) diglycolamide (T2EHDGA) have been identified as promising extractants for actinide partitioning from high-level nuclear waste. These extractants are proposed to be used along with suitable phase modifiers, viz. N,N-dihexyl octanamide (DHOA), tri-n-butyl phosphate (TBP) and 2-decanol dissolved in n-dodecane. Hydrodynamic parameters, viz. density, viscosity and interfacial tension (IFT) are important for optimisation of hydrometallurgical process to ensure that there is no emulsion formation and to achieve desired phase disengagement rate. Densities and viscosities of the two extractants, viz. TODGA and T2EHDGA along with different phase modifiers have been measured over different range of compositions and temperatures (298333?K). The viscosity data have been used to calculate the activation energy for viscous flow for each composition of solvents. The IFT values have also been measured for different solvent compositions. The viscosity and IFT data of TODGA and T2EHDGA with 2-decanol as phase modifier appears suitable under hydrometallurgical conditions proposed for actinide partitioning. (C) 2011 Canadian Society for Chemical Engineering