Block copolymer E64B20E64, where E denotes oxyethylene, OCH2CH2, B denotes oxybutylene, OCH2CH (C2H5), and the subscripts denote number-average block lengths in repeat units, was synthesized by sequential anionic polymerization. Characterization was by gel permeation chromatography (for molar mass distribution) and 13C-NMR spectroscopy (for absolute molar mass and conformation of block architecture). Dynamic and static light scattering were used to study micellization and micelle properties of this copolymer in dilute aqueous solution and in the presence of naphthalene. Dynamic light scattering was used to analyze hydrodynamic radius, rh and hydrodynamic expansion factor, δh. Static light scattering was used to study micelle association number, Nw, thermodynamic expansion factor, δt, and thermodynamic radius, rt. The presence of naphthalene in micellar core increased Nw by 50% and increased micellar size.