The estimation of energy barrier to detachment of particles from a substrate was carried out. Detachment processes of 4 μm polyethylene particles from a quartz wall under the gravitational force in aqueous solutions were investigated by a direct observation technique. The magnitude of energy barriers was experimentally determined by the temperature dependence of the rate constant of detachment and was compared with that estimated theoretically from the superposition of electrostatic and London—van der Waals energies calculated using the experimental electrokinetic potentials and Hamaker constants, respectivley. Both were in fairly good agreement.