Surfactant self-diffusion coefficients have been measured on a binary system of 1-O-beta-3,7-dimethyloctyl-D-maltopyranoside (beta-Mal(2)(Ger))/ water and a mixed surfactant system of beta-Mal(2)(Ger)/1-O-beta-3,7-dimethyloctyl-D-lucopyranoside (beta-Glc(Ger))/water at 25 degrees C. For comparison, measurements have also been made on 1-O-beta-decyl-D-maltopyranoside (beta-Mal(2)C(10))/water and beta-Mal(2)C(10)/1-O-beta-decyl-D-glucopyranoside (beta-GlcC(10))/water. The hydrodynamic radius of beta-Mal(2)(Ger) micelles obtained from the micellar diffusion coefficient is around 3 nm and nearly equal to that of beta-GlcC(10) micelles within experimental error. In the mixed surfactant systems, the hydrodynamic radii for both systems increase with increasing XG (the mole fraction of beta-Glc(Ger) or beta-GlcClo in the total mixed solute) above X-G congruent to 0.4 when the total surfactant concentration is kept constant at 2 wt%. The RH of beta-Glc(Ger)/Mal(2)(Ger) micelles increases more rapidly than beta-GlcC(10)/beta-Mal(2)C(10) micelles, and then phase separation occurs at X-G congruent to 0.65. On the other hand, the R-H of beta-GlcC(10)/beta-Mal(2))C-10 micelles continues to increase until the phase separation occurs at X-G congruent to 0.92. Measurements have also been performed as a function of total surfactant concentration at constant X-G (= 0.6). The CMC of the beta-Glc(Ger)/Mal(2)(Ger) system is larger than that of the beta-GlcC(10)/beta-Mal(2)C(10) system as expected from the results of the pure surfactant systems published previously. The RH increases with increasing total surfactant concentration for both systems. At higher concentrations, the RH of beta-Glc(Ger)/Mal(2)(Ger) micelles increases more rapidly than beta-GlcClo/beta-Mal(2)C(10) micelles. These results can be explained by the fact that the geranyl and decyl chains have the same volume but different chain lengths. (c) 2006 Elsevier Inc. All rights reserved.