The diffusivity and micellar size of polyoxyethylene nonionic surfactants, C10En (n = 4, 6 and 8), Triton X-100 and Triton X-405, were investigated using the dynamic light scattering method in this work. This study focused on studying the dilute surfactant solutions with concentrations of only a few times cmc. The effects of the concentration and temperature on micellization are discussed. Experimental data indicate that for the nonionic polyoxyethylene surfactants in this study: (1) the micelles grow as the temperature increases and (2) surfactants with longer hydrophilic EO groups form smaller micelles.