Solid-liquid equilibria (SLE) for the binary systems of 4-methoxyphenol + catechol, + ethylenediamine, and + piperazine and the enthalpies of fusion of the pure compounds are reported. The experimental results show that a single eutectic point exists in Li-methoxyphenol + catechol and a 2:1 complex compound is formed in both 4-methoxyphenol + ethylenediamine and 4-methoxyphenol + piperazine. The Wilson model was employed to correlate the SLE data of 4-methoxyphenol + catechol, and the ideal-chemical model (ICM) was used for correlating the equilibrium data of the complex formation-systems.