We have investigated the extent to which alkylbenzenes exhibit surfactant properties in diiodomethane (DIM) as solvent. As a result of its dipole moment and high refractive index, DIM has a high cohesive energy density arising from dipole-dipole and dispersion forces. DIM has a high affinity for the benzene group of an alkylbenzene solute but low affinity for the alkyl chain. These different affinities endow alkylbenzenes with amphiphilic properties in DIM solution, causing them to adsorb at the DIM-air surface and to aggregate. Surface tensiometry measurements show that the adsorption of alkylbenzenes at the DIM-air surface increases with the alkylbenzene chain length, consistent with the notion that the antipathy between the DIM solvent and the alkyl chain of the alkylbenzene provides the main driving force for adsorption. Ellipsometry measurements confirm the adsorption of octyl- and hexylbenzenes at the DIM-air surface and also indicate multilayer adsorption of octylbenzene at high concentrations. Using dynamic light scattering it is shown that octylbenzene forms aggregates in DIM at concentrations higher than 5 mol %. The apparent aggregate hydrodynamic radius increases from 0.6 nm at low concentrations to 1.5 nm at high concentrations.