Estimation of contaminant transport parameters in porous media is often constrained by the inability to measure pore-scale phenomena. Use of x-ray computed tomography (CT) may provide a tool to measure fluid transport at the pore-scale to facilitate estimation of transport parameters. The objective of this study was to use x-ray CT methods to measure transport of an iodide tracer in porous media and estimate porosity, solute pore-water velocity and solute dispersivity. CT-measured breakthrough curve experiments were conducted in columns of glass beads ranging from 1.4 to 8.0 mm in diameter with four sizes. Iodide breakthrough experiments were conducted using a...