The nonlinear dielectric effect (NDE) has been studied in o-bromochlorobenzene and m-bromochlorobenzene, and their solutions in benzene. On the basis of NDE results and the values of electric permittivity ε, density d, and refractive index n obtained in this work, the molar polarizabilities: linear ⟨μ^{2}⟩ and nonlinear ⟨μ^{4}⟩ were calculated. Assuming dipolar association of the investigated dihalogenobenzenes molecules to be restricted to dimerization, the Gibbs energy ΔG^{0}_{dim} of the dimerization process as a function of the Onsager field factor f(ε) is determined, which allowed us to draw a conclusion on the structure of associates.