Experimental osmotic second virial coefficients are reported for linear and star poly(ethylene oxide) in water and 1-propanol in the temperature region 25-55 degreesC. All measured osmotic second virial coefficients are positive. Ar. fixed temperature, the osmotic second virial coefficient for star poly(ethylene oxide) is lower than that for the linear polymer of comparable molecular weight. The osmotic second Virial coefficient for star poly(ethylene oxide) decreases with rising temperature in both water and 1-propanol. (C) 2001 Elsevier Science Ltd. All rights reserved.