Compositions comprising hexahydrophthalate (HHPA) metal salts may be useful as nucleating agents in polyolefins. Masterbatch compositions containing such salts and silica and/or hydrotalcite are particularly useful in reducing haze and improving properties of manufactured polyolefin articles or film. Such compositions may be dispersed effectively and efficiently into resin during manufacturing operations in the form of a masterbatch, thereby providing excellent polymer crystallization temperatures, improved polymer physical properties, improved dimensional stability, and improved transparency.