Ospreys (19) 43
Tries: Wells, Hook, S Williams, Bowe, Byrne, R Jones. Cons: Hook 5. Pens: Hook.
Ulster (0) 0
Bowe scored Ospreys' fourth try against former side Ulster
Ospreys took over at the top of the Magners League as they brushed aside a poor Ulster at the Liberty Stadium.
The home side was three tries to the good by half-time as Rhodri Wells, James Hook and Shane Williams finished off a glut of Ospreys possession.
Tommy Bowe secured the bonus point soon after half-time as he broke away against his former team.
Gavin Henson returned to action for the first time since April, coming off the bench, as Ospreys closed out the game.
Hook missed an early penalty kick that was simple by his standards, but a sweeping backs move soon garnered a try.
Williams ducked under a tackle before breaking up his left wing and then passed inside to Adam Jones.
Wells was on his prop's shoulder like a good scrum-half should be and took the ball in his stride to go over.
Hook again failed with the kick but made amends with a try on 14 minutes, doing well to hold onto a pass that was behind him after Lee Byrne had smashed through two Ulster defenders.
Hook struck the conversion but that was followed by the centre's second penalty miss.
However, it scarcely seemed to matter as the Ospreys claimed their third try in quick succession.
Fly-half Dan Biggar put big air on his pass out right to find Williams, off his wing, joining the line.
Ulster full-back Bryn Cunningham slipped at the crucial moment and collapsed helplessly in a pile as Wales' record try scorer motored past on his way to the line, Hook converting.
For the first 25 minutes Ulster had been pinned firmly back in their half, but at last they managed to gain some meaningful possession to force their way into Ospreys territory.
Ospreys open-side Marty Holah went off his feet at a ruck and Clinton Schifcofske stepped up hoping to get Ulster on the scoreboard, only to shank his kick to the left.
The wing had a second chance as the half came to an end but again curved his kick across the face of the posts.
Ospreys started the second half with the same attacking intent and it took a scrambling defence to drag wing Nikki Walker into touch as he bore down on the left corner flag.
Ulster's resolve was not helped by the 47th-minute sin-binning of back-row Matt McCullough for handling on the floor, Hook making his first three-pointer of the game from the resulting penalty.
A fourth Ospreys try soon followed to claim the bonus point, but it was a bitter-sweet moment for the scorer.
Hook seized the ball as Ulster spilled possession and drove a deep kick upfield for Bowe to chase.
The Ireland man, on his first return to his former side, won the foot-race to seal another seven Ospreys points but could barely muster a smile.
With the game won and all five match points on offer secure, Ospreys coach Sean Holley made use of his bench which included returning Henson to action after a long-term ankle injury.
The Wales and Lions back earned a big cheer from the home Liberty Stadium fans and was soon in the thick of the action.
Ulster lost another player to the sin-bin, as referee Peter Allan lost patience with prop BJ Botha at the scrum and Byrne soon added a fifth home try with 10 minutes remaining.
The Ulster blind-side defence was there in numbers but not in spirit as the full-back took a pass from the base of a ruck and went through unmolested.
Stephen Ferris became the third Ulster player to earn a yellow card and the visitors' overworked defence soon shipped another try, as replacement back-row Ryan Jones was shoved over.
Ospreys top the table on 19 points but could be overhauled by Munster on Sunday if they can win their match at Leinster.
Ospreys: Lee Byrne; Nikki Walker, Tommy Bowe, James Hook, Shane Williams; Daniel Biggar, Rhodri Wells; Paul James, Richard Hibbard, Adam Jones, Andy Lloyd, Ian Evans, Jonathan Thomas, Marty Holah, Tom Smith.
Replacements: Huw Bennett for Hibbard (63), Duncan Jones for A. Jones (63), Ian Gough for Lloyd (58), Ryan Jones for T. Smith (63), Rhys Webb for Wells (56), Andrew Bishop, Gavin Henson for Biggar (63).
Ulster: Bryn Cunningham; Timoci Nagusa, Rob Dewey, Andrew Trimble, Clinton Schifcofske; Niall O'Connor, Isaac Boss; Justin Fitzpatrick, Nigel Brady, BJ Botha; Carlo del Fava, Ryan Caldwell, Matt McCullough, Kieron Dawson, Robbie Diack.
Replacements: Stuart Philpott for Brady (66), Tom Court for J. Fitzpatrick (51), Ed O'Donoghue for Caldwell (67), Stephen Ferris for McCullough (59), Paul Marshall for Boss (68), Ian Humphreys for O'Connor (70), Paul Steinmetz for Cunningham (30).
Referee: Peter Allan (SRU).