During organosolv pulping of fiber hemp (Cannabis sativa L) with a mixture of ethanol/water, delignification is catalyzed by released acetic acid and formic acid in the effluent. The major sources of acetic acid are the acetyl groups, as determined by means of the acetyl balance, whereas formic acid is mainly formed as degradation product of polysaccharides. Trace amounts of other short chain organic acids and furans, formed from cellulose and hemicellulose, are also present in the effluent. A relatively simple and reliable HPLC method is described to analyze simultaneously the carboxylic acids and furans quantitatively. Acetyl and formyl contents of hemp core (4.3% and 0.2% respectively) and hemp bast (1.3% and 0.2%) are also analyzed with HPLC after an alkaline saponification.