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This study aims to characterize erythromycin (ERY) estolate by thermogravimetry analysis and differential scanning calorimetry. For such a purpose, compatibility testing has been conducted using binary mixtures of four excipients (magnesium stearate, sodium starch glycolate, povidone and mannitol). A comparison of simulated and experimental TG curves was made using Pearson's correlation coefficient so as to determine possible incompatibilities by the formation of volatile thermal degradation products. (r2 of around 0.91 was found for mixtures of magnesium stearate and mannitol, i.e., there might be interactions.) Dynamic thermal FT-IR spectroscopy and multivariate curve resolution (MCR-ALS) were used to identify incompatibilities before the occurrence of mass loss observed due to the chemical decomposition found through the TG. Infrared pure profiles were obtained as a function of the temperature of each component, thus revealing that it is an important and promising tool for monitoring solid-state phase transformations. Thereby, this methodology confirms that ERY shows incompatibilities regarding magnesium stearate and mannitol, and compatibilities concerning povidone and sodium starch glycolate. [ABSTRACT FROM AUTHOR]