Arsenal moved two points clear at the top of Champions League Group G after this win over Portuguese side Porto.
Henry gave Arsenal a first-half lead
The 2004 winners frustrated Arsenal for most of the first half before Thierry Henry's precise header put them ahead.
Arsenal doubled their lead soon after the break when William Gallas and Henry set up Alexander Hleb, who shot home.
Hleb's goal killed any hopes Porto had of rescuing the game, though late on Ricardo Quaresma tested Jens Lehmann with a strong shot after a mazy run.
Just as Henry had done in the Champions League final last May, Arsenal's captain led by example, though unlike in Paris, the French striker managed to score.
He was quick to embrace Emmanuel Eboue for his part in Arsenal's opening goal and Henry was always willing to track back - at one point he was to be found on the edge of his own box tackling Raul Meireles.
Before Henry gave Arsenal the lead for his 50th European goal, Kolo Toure thought he had scored early on with a close-range effort.
But the goal was ruled out with the linesman correctly judging the ball had been out of play before Cesc Fabregas passed to the Ivory Coast defender.
In that bright Arsenal start, Robin van Persie was busily engaged just as he had been against Hamburg in the Gunners' opening Champions League group game a fortnight ago.
As early as the third minute Porto's goalkeeper Helton was scrambling across his line to get down a low left-footed Van Persie shot.
Van Persie was less convincing on his other foot, blasting the ball over the bar with just Helton to beat after Henry slipped a delightful pass to the former Feyenoord forward.
Undeterred by that miss, Van Persie tried his luck with another low shot that Helton again did well to parry.
Having failed to beat Helton with an array of shots, Arsenal went ahead with a header.
The goal owed much to Eboue's ebullience as the Arsenal defender's speed and invention gave him just enough space to get past Marek Cech and deliver a superb cross to the far post.
Lurking in that space was Henry, who got the better of his marker Pepe to direct a header past the static Helton.
Just before the half-time whistle, Helton was troubled by another header, this time from Van Persie, but the Porto keeper did well to keep the ball out of the net.
Porto made two substitutions at the start of the second half - Raul Meireles and Lisandro Lopez coming on - but within three minutes of the restart the visitors found themselves two goals behind.
Arsenal's second owed much to Gallas, who rode a succession of tackles, before touching the ball to Henry.
The Gunners captain quickly passed to Hleb, who drilled a low shot past Helton.
Tomas Rosicky should have added a third, only to balloon the ball over the bar, while Fabregas went close with a shot after more good work by Henry.
Porto were pitiful in attack though late on Quaresma's shot saw Lehmann need two attempts to claim the ball.
Arsenal: Lehmann, Eboue, Toure, Hoyte, Gallas (Song Billong 90), Hleb (Walcott 85), Fabregas, Silva, Rosicky, Henry, Van Persie (Ljungberg 74).
Subs Not Used: Almunia, Julio Baptista, Adebayor.
Booked: Rosicky, Silva.
Goals: Henry 38, Hleb 48.
FC Porto: Helton, Bosingwa, Pepe, Bruno Alves, Cech, Gonzalez, Paulo Assuncao, Ricardo Costa (Raul Meireles 45), Anderson (Adriano 65), Quaresma, Postiga (Lopez 45).
Subs Not Used: Vitor Baia, Sektioui, Fucile, Jorginho.
Booked: Ricardo Costa.
Ref: Stefano Farina (Italy).