This investigation reports preparation of polyurethane and polyurethane/clay nanocomposites based on polyethylene glycol, isophorone diisocyanate (IPDI), an aliphatic diisocyanate and 1,4- Butanediol as chain extender by solution polymerization. In this case PU/clay nanocomposites were prepared via ex-situ method using 1, 3, and 5 wt % of Cloisite 30B. Thermogravimetric analysis showed that the maximum decomposition temperature (T-max) of the PU/clay nanocomposite is much higher than the pristine PU. The tensile properties improved upon increasing the organoclay (Cloisite 30B) content upto 3 wt %, and then decreased to some extent upon further increasing the nanoparticle loading to 5 wt %. Optical properties of the nanocomposites were studied by UV-vis spectrophotometer. X-ray diffraction (XRD) and transmission electron microscopy (TEM) were used to study the morphology of the nanocomposites. It was observed that with the incorporation of 3 wt % nanoclay the crystallinity in PU nanocomposite increases, then diminishes with further loading. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3328-3334, 2013