Pyrolysis of lignocellulosic biomass with acidic pre-treatment to produce valuable bio-chemicals has been carried out in an integrated pyrolysis-gas chromatograph/mass spectrometry system. Three different waste biomasses (fir wood sawdust, pine wood sawdust and nutshell) were subjected to acidic solution to specify the acid pre-treatment effect on biomass chemical structure, thermal degradation profile and pyrolysis products. Post acid pre-treatments, the changes in the biomasses and thermal degradation profile were studied through proximate, structure and ultimate analysis and thermogravimetric. The pre-treatment significantly reduced the inorganic, cellulose and hemicellulose content in biomass samples. According to the pyrolysis experime...