Arsenal moved up to fourth in the Premiership after a sparkling display.
Alexander Hleb combined with Tomas Rosicky for Arsenal's second
Thierry Henry needed only 58 seconds to score Arsenal's first goal at the Madejski Stadium, the striker stroking home Cesc Fabregas' precise pull-back.
Alexander Hleb doubled the lead after exchanging passes with Tomas Rosicky and Robin van Persie finished another fast-flowing move after half-time.
Thierry Henry converted a penalty after Marcus Hahnemann's foul on Fabregas as Arsenal completely outclassed Reading.
With title rivals Manchester United and Chelsea both wrapping up victories before Arsenal had kicked off, the Gunners were under pressure to secure the three points to keep them in touch.
They wasted little time in stamping their authority on the game, the first league meeting between the two sides.
Fabregas received the ball on the right, nonchalantly brushed aside James Harper's challenge and cut the ball back for Henry to score his 168th Premiership goal.
The sublime goal set the tone for a sumptuous attacking display from the Gunners.
Henry and Fabregas combined again after five minutes but Reading defender Ivar Ingimarsson was alert to the danger and smothered the teenager's shot.
Reading threatened an unlikely equaliser through Seol Ki-Hyeon but Jens Lehmann tipped over the South Korean's fierce volley - and Arsenal were soon 2-0 ahead.
Hleb collected Tomas Rosicky's return pass and blasted the ball off Hahnemann's arm and into the roof of the net.
Had Van Persie been less selfish, Arsenal might even have been further ahead at the interval.
The Dutch striker twice went for goal with his team-mates screaming for the ball, while he also blazed a free-kick over the bar.
Steve Coppell opted for a change at half-time, Brynjar Gunnarsson replacing Ulises de la Cruz at right-back but within four minutes of the restart, the Reading boss watched in horror as the hosts' defence was sliced open again.
Hleb collected Henry's through ball and cut it back for Van Persie to slot home.
Reading, for whom striker Shane Long made a first Premiership start, were in danger of being overrun but, to their credit, they kept their heads up.
Coppell's side even came close to a goal when Stephen Hunt shot over but Arsenal hit back immediately.
Fabregas was clearly caught by Hahnemann as he bore down on goal and Henry coolly converted the penalty to make it 4-0.
With 20 minutes still left to play, the Gunners relaxed, allowing Reading some long spells of possession, but the hosts could not find a consolation as an in-form Arsenal posted their fifth successive league win.
Reading manager Steve Coppell:
"Right from the first attack when Arsenal scored, that put us in a difficult position.
"With the quality they have, on the field and on the bench, we were always going to be chasing the game.
"We played as well as we were allowed to. There was a spell in the last 15 minutes when we did really well, despite being 4-0 down."
Arsenal manager Arsene Wenger:
"We had a good start, played well and our movement and our technique made the difference.
"We dominated the game. In the last 20 minutes our concentration dropped but overall I am very happy.
"I'm not sure if that was our best performance of the season. We can improve - the team is getting better."
Reading: Hahnemann, De la Cruz (Gunnarsson 46), Sonko, Ingimarsson, Shorey, Ki-Hyeon (Oster 77), Sidwell, Harper, Hunt, Long (Little 73), Doyle.
Subs Not Used: Stack, Lita.
Arsenal: Lehmann, Hoyte, Toure, Djourou, Gallas, Rosicky (Song Billong 77), Fabregas, Silva, Hleb (Adebayor 73), Van Persie (Walcott 73), Henry.
Subs Not Used: Almunia, Clichy.
Goals: Henry 1, Hleb 39, Van Persie 50, Henry 70 pen.
Ref: A Wiley (Staffordshire).