Miscibility, structure and property relationships were studied by different techniques for various polymer pairs, four blends of polystyrene (PS), styrene-acrylonitrile copolymer (SAN), polycarbonate (PC) and polyphenylene oxide (PPO) [PS/PPO, PS/PC, PS/SAN and PPO/SAN] were investigated in the entire composition range. Glass transition temperatures were measured by DSC, mechanical properties were characterized by tensile test, methanol absorption was determined at 50 degrees C. The Flory-Huggins interaction parameter (chi) was derived from Hildebrand solubility parameters, and compared to chi-related quantities calculated from the experimental results. Good correlation was obtained between parameters derived from different methods used for the characterization of polymer/polymer interaction.