Dispersion is a key process controlling gas and solute transport in porous media. Performing dispersion tracer tests for solutes is generally much more time consuming than for gases. Ability to estimate solute dispersion based on gas dispersion data is therefore advantageous. The aim of this study was to investigate the relationship between solute and gas dispersion in selected porous media to develop a procedure for estimating solute dispersion from gas dispersion. Solute (NaCl) and gas (O2) breakthrough curves were measured at different fluid (water and gas) velocities (at identical Reynolds numbers for the two fluids). A commercial crushed granite, available in multiple particle sizes, was used as porous medium. NaCl and O2 dispersion coefficients were determined from measured breakthrough data and used to calculate solute and gas dispersivity as a function of particle size (Dm) and particle size range (R). Both solute and gas dispersivity increased with increasing R, and decreasing Dm. A simple relationship between dispersivities was found.