Radical UK preacher Anjem Choudary is one of two men who has been charged with inviting support for Islamic State militants, Scotland Yard says.
He and another man, Mohammed Mizanur Rahman, have each been charged with one offence under section 12 of the Terrorism Act 2000.
They were due to appear at Westminster Magistrates' Court on Wednesday.
Mr Choudary, 48, of Ilford in east London, and Mohammed Rahman, 32, of Whitechapel in east London, were arrested on 25 September last year on suspicion of being members of IS, which is a proscribed organisation.
Proscription means membership of the militant group is a criminal offence, and that the organisation cannot lawfully operate in the UK.
Sue Hemming, of the Crown Prosecution Service, said: "It is alleged that Anjem Choudary and Mohammed Rahman invited support for Isis [also known as IS] in individual lectures which were subsequently published online."
Source: BBC