Pyrolysis-GC-MS is a rapid process for analysis of rather complex organic compounds. The method has great application to petroleum shale oil and wood lignin. Small powdered samples (several mg) are placed in silica capillary tubes and rapidly heated in an inert atmosphere such as He or N2. Breakdown products of the pyrolysis are then trapped and held for an allocated time in an injector attached to a gas chromatograph (GC) before being introduced. Once introduced, the sample stream is chromatographed on a capillary column with programmable temperature control before being split into two streams. The first stream containing most of the sample travels directly to the GC detector and the second stream is electronically ionized and the fragmentation patterns read on a mass spectrometer (MS). All information is collected and stored for later retrieval and analysis by a large computer. The computer has software that can compare the fragmentation patterns of the compounds on the GC with known compounds stored in its library. Apart from uses already mentioned, there is great potential for use in lignin analysis of woods and wood products. Results to date indicate pyrolysis-GC-MS is extremely useful for characterisation of lignin from phenolic monomers in the pyrograms. Quantitation of these monomers is being studied.