Some pertinent physical properties were determined for thirty-two diethers and related compounds whose structures indicated that they might be good uranium extractants. Correlation of these properties with structures indicates that the use of the carbon to oxygen atomic ratio as a guide to the extraction power of an ether cannot be extended beyond a particular homologous series nor used when the spacing of the oxygen atoms in the ether is changed. The dipole moment appears to be a factor in explaining the differences in the extraction power of compounds with the same carbon to oxygen ratio. The lower-membered dialkoxypentanes showed suitable physical properties and adequate uranium extraction capabilities. These were examined more thoroughly with respect to their use as uranium extractants in large scale recovery operations.