The miscibility in blends containing poly(methyl methacrylate-co-methacrylic acid) [P(MMA-co-MA)] as polymer component and the dihydric phenols 4,4'-thiodiphenol (TDP) and 4,4'-methyllendiphenol (MDP) as low molecular weight compounds (LMWC) was studied by Differential Scanning Calorimetry (DSC) and Fourier Transform Infrared Spectrophotometry (FTIR). Thermal properties, such as the glass transition of P(MMA-co-MA) and the melting of the LMWC, were found to be clearly affected when the compounds were blended, which was attributed to the miscibility between them. FTIR was used to investigate the specific interactions between P(MMA-co-MA) and the LMWC. The formation of intermolecular hydrogen bonds between the carbonyl groups of P(MMA-co-MA) and the hydroxyl groups of TDP and MDP were discovered. Thermogravimetric and viscometry analysis were also used as additional techniques to complement the obtained FTIR and DCS results