Steve Smith
Smith struck a ton as Australia declared 492 for nine at the Oval. (Reuters)

A century from Steve Smith ensured Australia ended the second day of the fifth Test of the Ashes series in a commanding position at the Oval leaving England trailing by 460 runs.

The tourists declared 492-9 as Smith finished unbeaten on 138 as he secure his maiden Test ton on a rainy afternoon in south London, as Shane Watson also secured a century as Australia racked up an impressive tally having gone into tea on 397-6.

Joe Root (13 not out) and Alistair Cook (17 not out) got England's reply off to a steady start before an afternoon which didn't get started until 2:30pm was called to an end.

Brad Haddin (30) and Ryan Harris (33) provided support for Smith as he struck a spectacular six from Jonathan Trott's effort to mark a memorable day for the 24-year-old in emphatic fashion. Trott responded however, removing Haddin just four balls later.

Debutant Chris Woakes won his first Test wicket when James Faulkner was caught by the boundary by Trott for 23 after tea, and the Aussie paceman was soon joined by Mitchell Starc who made his way to the pavilion after Graeme Swann's delivery after hitting 13 off eight balls as the Aussies stalled to 446 -8.

After striking a couple of fine sixes, Harris would be the next to follow after slicing an effort high in the air before James Anderson followed the ball to take an impressive over-the-shoulder catch.

Nathan Lyon was introduced but didn't get the chance to improve on his side's score as captain Michael Clarke declared with the man of the day Smith not out.

With a much-shortened session to mount their response, Cook and Root calmly laid the ground work for day three, racking up a 32 between the two of them.