Abstract The hydrolysis of phthalates and other synthetic organic esters (SEs) in the indoor environment may be connected with poor indoor air quality and “sick building syndrome.” We have made laboratory measurements of the alkaline hydrolysis kinetics and mechanisms of 2,2,4‐trimethyl‐1,3‐pentanediol monoisobutyrate (TMPD‐MIB), butylparaben (BP), bis(2‐ethylhexyl) adipate (DEHA), and butyl benzyl phthalate (BBzP) in bulk aqueous solutions at room temperature, using UPLC‐QToF‐MS to detect the reactants over the course of the reactions. The determined alkaline hydrolysis second‐order rate constants for TMPD‐MIB, BP, DEHA, and BBzP at pH 13 were (9.8 ± 1.3) × 10 −3 M −1 s −1 , (1.24 ± 0.17) × 10 −4 M −1 s −1 , (4.8 ± 0.6) × 10 −4 M −1 s −1 , and (5.9 ± 0.8) × 10 −2 M −1 s −1 , respectively. The results suggest that hydrolysis may be a major degradation pathway for these compounds in the indoor environment under alkaline conditions.