derived water-soluble maleamic acid derivatives. The results reveal that the number, structure, and position of the substituents on the cis-double bond exhibit a significant effect on the pH-related hydrolysis kinetics and selectivity of the maleamic acid derivatives. Interestingly, for the mono-substituted citraconamic acids (α-/β-isomer), we found that their hydrolyses are accompanied by the isomerization between the two isomers.