Meyssan's book 9/11: The Big Lie (L'Effroyable imposture) challenges the official account of events of the September 11 terrorist attacks.

[2] Meyssan is president of the Voltaire Network, which had been a respected independent think tank prior to the publication of 9/11: The Big Lie.

[2] Meyssan has been noted as using cross-citations of other conspiracy theorists' works in order to lend the appearance of credibility to his ideas.

Meyssan argued that the attacks were organized by a faction of the US military–industrial complex in order to impose a non-democratic regime in the United States and to extend US imperialism.

[5] A follow-up to his first book titled L’effroyable Imposture II (The Big Lie 2) accused Israel of carrying out the assassination of Rafic Hariri.