Ensemble Européen / O'Reilly, St John's, Smith Square, London

This opening concert of the annual Lufthansa Festival of Baroque Music went from the sublime to the ridiculous - though, happily, by design rather than accident.

This year's theme is the Italian commedia dell'arte tradition and its ramifications. But the festival's artistic director, Kate Bolton, rightly decided she must first celebrate the tercentenary of Marc-Antoine Charpentier (1643-1704). Fortunately, his imposing output runs to some very jolly commedia items.

The performers were the Ensemble Européen William Byrd, a group of young singers and period players coached and run (along the lines of William Christie's Les Arts Florissants) by the Australian scholar-conductor Graham O'Reilly. Their sound is quite distinct, however: less polished, more pungently individualised - and, possibly, nearer the noise one might have heard in the 17th century.

This was apparent in Charpentier's Salve regina, H24, for three choirs and continuo. Moving from tightly worked contrapuntal paragraphs on motifs from plainchant to transfixing chordal effects, this setting runs into and beyond dissonances as bold as anything in Charpentier's younger contemporary, Purcell.

There was nothing so striking in Charpentier's early pocket oratorio on the Last Judgement, Histoire sacrée: Extremum Dei Judicium, H401, for soloists, two choirs, strings and continuo. God (the bass-baritone Alain Buet) announces the end of time; the chorus voices its horror; oboes and kettle drums sound a last trump, and so on. But the hustling sequence of the dead coming back to life and the serene chorus of the elect at the end were memorable.

The second half was given over to the music Charpentier composed in 1673 for the first run of Molière's last comedy, La malade imaginaire - fateful, because Molière took the title role, only to die for real after the fourth performance. The score comprises a busting overture and music for three intermèdes. In the first, the lovelorn commedia figure Pulcinelle is mugged by four corrupt Night Watchmen; the last is a grotesque lampoon on the medical profession.

But the Deuxieme Intermède is another matter. Here, the longings of young love are hymned by four Moorish Women in long, voluptuously plaintive paragraphs over slow triple-time bass lines. Surely Purcell must have remembered this when he came to write the setting of Dryden's hymn to the pleasures of love in King Arthur?

Festival runs to 18 June (020-7222 1061)