Thermolytic acidolysis of polyamic esters (PAEs) in solid and solution states were elucidated. The polyamic esters were synthesized by direct polycodensation using a condesing agent, and inherent viscosites were ranged 0.34∼0.81 dL/g. The polymer films of PAEs with t-butyl ester were readily acidolyzed by contacting with various organic acids, but those of the methyl, ethyl, and isopropyl ester were intact. The solution acidolysis revealed that the polymic ester with t-butyl ester was solubilized in 2.38 wt% of tetramethylammonium hydroxide (TMAH) aquous solution after treated with p-toluene sulfonic acid for 3 minutes at 50℃. In solid state, acid catalyzed thermolysis temperature of PAE with t-butyl ester was shifted to lower temperature, but those of the other chemical reactions, such as loss of water and polyimide decomposition were unchanged. The effluent gas at 1st decomposition of the PAE was identified as isobutene. It implied that the thermolytic acidolysis was proceeded via the formation of polyamic acid and isobutene.