Diluent effect on the solvent extraction and membrane transport properties of Am(III) using TODGA (N,N,N',N'-tetraoctyl-3-oxapentanediamide) as extractant/carrier have been investigated in detail. The diluents studied were n-dodecane, 1-octanol, tert-butyl benzene, kerosene, toluene, carbon tetra chloride, chloroform, 1,2-dichloroethane, and nitrobenzene. The distribution ratio values of Am(III) with TODGA as the extractant were correlated with various diluent parameters. The nature of the extracted species formed was also determined for the different diluents. Supported liquid membrane (SLM) transport studies were carried out and the ease of Am transport followed the trend: toluene > n-dodecane > kerosene > 1-octanol > tert-butyl benzene similar to CCl4 > CHCl3. Effect of membrane pore size on Am(III) transport for each of the diluents have been evaluated. Membrane diffusion coefficient values have been calculated using Wilke-Chang equation and compared with those determined experimentally using a t(lag) method. (C) 2012 Elsevier B.V. All rights reserved.