Caetano Veloso, Barbican Hall

He's a small man, wiry, bespectacled. His three band members - guitarist Pedro Sá, bassist Ricardo Dias Gomes, percussionist Marcelo Callado - must each be about a third his age: a case of three pupils and a professor? Behind them is a screen which, through this one-and-a-half-hour set, will flash up clips of Brazilian seascapes and city scenes, mainly of Rio de Janeiro.

Between band and screen is what looks like the wings of a paraglider. It's an odd prop, but people are always paragliding theatrically, perhaps ostentatiously, from and across the vertiginous hills of Rio. Maybe our wiry singer, Caetano Veloso, is claiming: I can join you but I know my place - stage-bound, a perfomer as exotic as any of you avian adventurers, with a voice which aspires to higher clouds than any of you will see.

Have seen. For over 40 years Veloso has been entrancing, sometimes bamboozling, audiences with his wit, lyricism and confrontation, gathered in a voice that appears to have been hatched, yesterday, from honey. It's a male voice unlike any other on earth. It reaches effortlessly for the heavens.

I start with the voice deliberately. In so doing, I should also declare an interest, of sorts. When this Bahian musician stepped out on to a similar London stage, at the Royal Festival Hall in 1993 - he was then 51 - and opened his mouth to sing, I'd never heard anything like it. Caetano Veloso was quite new to me, and, for reasons to do with travel, music and writing, and a relationship with Brazil already begun (a book resulted four years later), it changed my life, though that's not strictly relevant here.

17 years on, there was a relevant, pressing question this single, London-summer appearance of Veloso's raised: how good could that voice, in its late sixties, have remained? The answer is, it's all still there: expressive, lithe, sensual, boyish. His falsetto is note perfect. With Veloso, to borrow from the French maxim, la voix, c'est l'homme. Everything he thinks and believes is channelled into a vocal miracle which seems to belong to a body, well, a third its owner's age.

I think this is what made this Barbican evening for some, perhaps for many, one of the most non-negotiable dates of this year's musical calendar. That said, his latest writing is brassy, urban, often riff-heavy, and a long way from the mischievous, sparkly Tropicalismo which made him and fellow Bahian Gilberto Gil notorious in the late 1960s.

His latest album zii e zie (uncles and aunts), with the junior trio playing not unlike Radiohead, had plenty of stage-time on Saturday night; but there was much of the classic Veloso on display too: the preening, the flirting, the arms curling sideways and upwards - and accompanying himself on acoustic guitar to a famous track, "Desde que o Samba e Samba" from his and Gil's 1992 album celebrating Tropicalismo.

Brazilians in the audience, pretty numerous, knew the words and sang along. So it was with half a dozen other famous songs, including a 1971 one in English about his sister Maria Bethânia (who, with curious serendipity, performs at the Royal Festival Hall on 17 July), written when he and Gil were in exile in London after being thuggishly bullied out of their country by the military in 1969.

The 1993 RFH gig was the first time Veloso had performed in London since that diffcult period. In my thoroughly prejudiced view, it was one of the most astounding nights of Latin music ever to have graced the capital. It was also three hours long. Since then, Veloso has cracked the States, released a dozen albums - not all of them brilliant - written a memoir, and remained a preposterously vibrant artist and, off stage, in interviews, quite lippy. He always was. On, his newer music can sound twee and sentimental, and, most recently, just brash.

I also felt the Barbican audience was a trifle shortchanged. With an advertised 7.30pm start, doors didn't open until 7.45pm. The music began at 8pm. On exit, the time I read on St Giles Cripplegate's clock was 9.30pm. There were so many other mesmerising songs this indecently prolific musician could have pleased us with, but Veloso has never been in the business of mere crowd-pleasing. At 51, he unleashed himself in London like a flock of Birds of Paradise, madly eager to occupy the sky - and find home. If at 67, on 3 July, his wings seemed a little clipped, he can be forgiven: he has nothing to prove and his soaring vocal energies are still unique in the world.

• Explore Caetano Veloso's website
• More from the Barbican's summer Blaze festival
• Theartsdesk's "Dinner with Caetano Veloso"