This study aims to measure the solid-liquid equilibria (SLE) of systems containing diphenyl carbonate (DPC) for production of high-purity DPC as required for a nonphosgene-based polycarbonate production process. SLE data for three binary systems: methanol + DPC, dimethyl carbonate (DMC) + DPC, and phenol + DPC, were determined at atmospheric pressure by visually observing the melting points of a wide range of compositions. An experimental apparatus to allow both accurate control of temperature and visual observation of melting was designed for this study, and the experimental apparatus and procedure were verified by measuring the SLE of the system 2-methyl-1H-imidazole + 1-dodecanol. The binary mixtures DMC + DPC were simple eutectic systems, and the eutectic point was determined. From the experimental SLE for the two binary mixtures methanol + DPC and phenol + DPC, a solid addition compound containing a 1:1 ratio of methanol or phenol and DPC can be expected. The experimental SLE data of the three binary mixtures were represented by the semi-empirical equation of Ott and Goates. A nonrandom two-liquid (NRTL) model was also used for the data reduction of the systems DMC + DPC.