Aldehyde-type lignin monomers like hydroxycinnamaldehydes are important monomers in plants downregulating the enzyme activity of cinnamyl alcohol dehydrogenase or catechol-O-methyltranferase. Cinnamaldehyde (CA) is the simplest aldehyde-type lignin model compound, which is also one of the primary products of cinnamic alcohol. In this contribution the experimental results obtained for the pyrolysis of trans-cinnamaldehyde (trans-CA) using a unique Py-GC×GC-FID/TOF-MS at temperatures from 573 to 1023 K are reported. Styrene and cis-cinnamaldehyde account for a large fraction of the total product yields at higher temperature. A dimer of styrene detected at higher temperatures (= 823 K) suggests the presence of radical reactions. The plausible pyrolytic pathways of major products are proposed. This study is a first step towards a successive model extension to other aldehyde-type monomers such as p-coumaryl, coniferyl and sinapyl aldehydes.