Irishman Paul McGinley carded the low round of the tournament with an 8-under 64. That moved him to 8-under-par 133 where he stands alone in second place.
Australian Nick O'Hern shot a round of 3-under 69 and stands at 7-under-par 137. Sweden's Peter Hanson and Irishman Padraig Harrington are one stroke further back at minus-6.
Hedblom, whose lone win came at the 1996 Moroccan Open, got his round going with a bogey on the par-4 first. He recovered with his second birdie in two days on the fourth on the West Course at the Wentworth Club.
The Swede moved to 5 under with a birdie on the eighth. Hedblom drained a birdie try on the ninth and made another birdie putt on 10 to get to 7 under.
Hedblom converted a birdie attempt on the 11th to keep his roll going. The 35- year-old capped a run of five straight birdies as he birdied the 12th, which gave him the outright lead at minus-9.
He cooled off with three straight pars. Hedblom then collected back-to-back birdies from the 16th to extend his lead to three strokes and finish one stroke shy of the course record.
'Sometimes things just run your way,' said Hedblom, who owns the 36-hole lead for the first time since the 1996 Moroccan Open. 'That's what happened today. Hopefully it can continue for another two rounds.'
McGinley had a quiet opening round with just two birdies and two bogies. Friday was a different story. He dropped a 8-iron within 6 feet of the hole to set up a birdie at the second.
The three-time winner on the European Tour stuck his third shot to the par-5 fourth within one foot and kicked in his birdie putt. McGinley sank another short birdie try on the sixth. He reeled off five straight pars around the turn.
McGinley drained a 12-foot birdie putt on the par-5 12th to jump to minus-5. The two-time Ryder Cupper then birdied the 14th to keep rolling. McGinley drained a 20-foot birdie putt on No. 16 and two-putted for birdie at the next to take second place by himself.
'Any time you shoot a score like that around Wentworth you've got to be happy,' McGinley said. 'If ever there was a comfortable 64, that was it. I hit every green in regulation apart from the first, which I missed by about two inches, and a couple of par-5s in two, obviously.'
Ben Curtis, the 2003 British Open champion, carded a 1-under 71 to move to 5-under-par 139. He was joined in a tie for sixth place by Peter Lonard, Lee Slattery, Thongchai Jaidee and Michael Campbell.
Reigning U.S. Open champion Retief Goosen posted his second straight round of 2-under 70. He shares 11th place at 4-under-par 140 with a plethora of players including Ian Poulter, Darren Clarke, Robert-Jan Derksen and first-round co-leader Jose-Filipe Lima.
Nick Faldo, a four-time winner of this tournament, shot a 1-under 71 and stands at 3-under-par 141. Jose Maria Olazabal is one of six other players at minus-3.
Peter Lawrie, who shared the lead with Lima and Graeme McDowell, stumbled to a 3-over 75 and shares 30th place at minus-2. Ernie Els and Scott Drummond, the defending champion, are also at 2-under-par 142. McDowell is one stroke further back at 1-under-par 143 after a 4-over 76.
The cut line fell at even-par 144 with 72 players advancing to the weekend. Niclas Fasth, Colin Montgomerie and Ian Woosnam survived on the number, while Eduardo Romero (145), Barry Lane (146) and Sandy Lyle (149) were among the cut casualties.