In the present work 1-butyl-3-methylimidazolium chloride (BmimCl) and 1-butyl-3-methylimidazolium acetate (BmimOAc) ionic liquids have been used for the dissolution of bamboo biomass. After dissolution the treated samples were precipitated by using water. The calorific value, CHNS content, lignin content, and proximate analysis of the untreated and precipitated material were measured. The BmimCl treated sample was found to have a higher value for calorific value, elemental percentage of carbon, and lignin content as well as fixed carbon, compared to the untreated and BmimOAc treated samples. The untreated and ionic liquid treated samples were also characterized by TGA and XRD. Low thermal stability and change in crystalline form from cellulose Type I to Type II have been observed by the dissolution and precipitation treatment. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was employed to achieve fast pyrolysis of the untreated and ionic liquid treated samples of bamboo. The desirable products with respect to bio-oil, such as phenols, furans, alcohols, hydrocarbons, and aromatics are increased, while the undesirable products such as aldehydes and ketones, except for total acids, are decreased for the BmimCl treated sample. © 2012 American Chemical Society.