Mostyn's try was converted by Paul Warwick and although Jones had cut the lead to a single point by the break through two penalties, the Ospreys had struggled up front - particularly at the lineout where Huw Bennett was having difficulty hitting his jumpers.
After the break Warwick slotted a penalty, only for Jones to reply with a well-taken drop-goal. But the Ospreys outside-half missed a chance to win the game when he pulled wide a routine shot 25 metres out with six minutes left on the clock.
The Ospreys: Adrian Durston; Stefan Terblanche, David Bishop, Elvis Seveali'i, Aled Brew; Matthew Jones(2PG, 1DG), Jason Spice (capt); Paul James, Huw Bennett, Andrew Millward; Andy Newman, Lyndon Bateman; James Bater, Richie Pugh, Andy Lloyd
Bench: Richard Hibbard, Cai Griffiths, Luke Tait, Nathan Bonner-Evans, Andy Williams, James Hook, Dave Tiueti. Replacements used: Tait for Bateman 50, Bonner-Evans for Lloyd 57, Tiueti for Brew 65
Connacht: Matt Mostyn(1T); Ted Robinson, Darren Yapp, James Downey, Conor McPhillips; Paul Warwick(1C, 1PG), Chris Keane; Ray Hogan, Bernard Jackman, Peter Bracken; Christian Short, Andrew Farley (capt); Mike Swift, Matt Lacey, John O'Sullivan (sin bin 37-45)
Bench: Gareth Halligan, Stephen Knoop, Piet Myburgh, John Muldoon, Conor O'Loughlin, Eric Elwood, Justin Meagher. Replacements used: Muldoon for Swift 12, Swift for Muldoon 28, Knoop for Bracken 50, Elwood for Robinson 57, Muldoon for Swift 70, O'Loughlin for Mostyn 74
Scoring sequence: 20' Mostyn (T) 0-5, Warwick (C) 0-7, 30' M.Jones (PG) 3-7, 38' M.Jones (PG) 6-7, 64' Warwick (PG) 6-10, 69' M.Jones (DG) 9-10
Referee: Graeme Hannah (Scotland)