He's used to people hanging on his every erudite word. Now Stephen Fry – actor, author, quizmaster of QI, enthusiastic tweeter and celebrated brainbox – has announced that he is to make a series for BBC2 about language.

"It's a bit of a secret but the BBC have commissioned me to do a five-part series on language, called Planet Word," he said. "Language is my real passion. So, I'm going to Beijing to interview the man who invented Pinyin, a phonetic version of the Chinese language. He's 105 years old … if he dies on me I'm going to be so annoyed."

Fry revealed details of his highbrow new project to 14-year-old Eden Parris in an interview for a Radio Times feature that enabled young readers to meet their TV heroes.

In a conversation that ranged from Harry Potter to Wagner, darts and porridge oats, Fry said: "I haven't seen a good documentary about language, where it comes from, how we speak it, the variations of it, whether languages are dying, whether we are better at speaking than we were. There are so many questions."

Fry – voted most intelligent man on TV in 2006 by RT readers – said his favourite words were Anglo-Saxon, "like bundle – what a lovely word", although followers of his Twitter feed are used to a livelier, more playful turn of phrase; last week he used "wowser", "brokenated" and "selfspank". A devotee of Oscar Wilde, he has presented two series of Fry's English Delight on Radio 4, discussing grammar and idiom.

He warned Parris that language could shape and limit people's ambitions: "We are not nouns, we are verbs. I am not a thing – an actor, a writer – I am a person who does things – I write, I act – and I never know what I am going to do next. I think you can be imprisoned if you think of yourself as a noun."

Fry added about his recent series on Wagner: "I think programmes only work if they matter to you, because I think audiences are smart – even though you wouldn't believe the BBC thinks so – and one thing they are particularly smart about is when a presenter is faking."

Last month, after delivering the Bafta annual television lecture in London, Fry complained to the audience about the "infantilism" of British TV.