The purpose of this study was to investigate the relationship between response to the bitterness taste sensor and physicochemical parameters of 47 pediatric medicines and to classify these medicines according to the biopharmaceutics classification system (BCS). Forty-seven bitter compounds, most of which were on the WHO model list of essential medicines for children (March 2017), were used in the study. Solutions (0.1 mM) were evaluated by an artificial taste sensor using membranes sensitive to bitterness. On the basis of principal component analysis of taste sensor measurements, chlorpromazine, haloperidol, propranolol, amitriptyline, diphenhydramine were predicted to express the strongest levels of basic bitterness, surpassing that of quinine. Correlation tests between bitter taste sensor outputs and physicochemical properties were then carried out and the compounds classified in terms of their biopharmaceutical properties. High log P values (≥2.82), physiological charge (≥1), low log S values (<−3) and small polar surface area (PSA; <45.59 Ų) were found to correlate significantly with the responses of bitter taste sensors. Forty-one of the 47 compounds could be placed into one of four groups in the BCS, on the basis of dose number ( D ₀), an indicator of solubility which takes into account clinical dosage, and fractional absorption (Fa). For medicines classified in group 4, the factors D ₀ > 1 and Fa < 0.85 significantly correlated with the responses of the taste sensor for basic bitterness. It was concluded that lipophilicity, physiological charge, solubility, PSA and D ₀ are the main factors affecting the bitterness of pediatric medicines.