The 31-year-old Spaniard has been in good form of late and, having been in a three-way tie for the lead after round one, he is now out on his own.
After beginning his round on the 10th, the two-time European Tour winner picked up shots at 12, 13 and 16, before chipping in for an improbable birdie at the par-five 18th, after putting his approach shot into the water.
Further birdies came his way at the first and second but he gave one shot back when he failed to get up-and-down from a bunker at the eighth.
Cabrera-Bello is a shot clear of England???s James Morrison, who won last month???s Spanish Open and birdied three of his last four holes to follow up his opening 67 with a 66.
Another of the first round joint-leaders, Denmark???s Lasse Jensen (69), is in a tie for third with Michael Hoey of Northern Ireland, who had nine birdies as he shot a 65, the joint-best round of the day.
World No 7 Henrik Stenson added a 71 to his opening 67 and is in a big group at six-under-par, which also includes the other first-round leader, Daniel Gaunt of England, who carded a 73.
But Stenson???s playing partner Martin Kaymer (71) missed the cut by a shot after a costly bogey at the last left him on one-under-par.
Kaymer???s drive on the 18th was deemed not to have crossed a water hazard, following a lengthy discussion involving rules officials and on-course reporters, who were being fed information from television replays.
Kaymer said: ???At the end of the day, too many people got involved.
“I could not see where it crossed the water. It was up to the camera guys and they were not sure and they (the referees) have to give the benefit to the field.”
Meanwhile, Cabrera-Bello is in a good position once again, having finished fourth, 13th and second in his last three events on the European Tour.
However, he bogeyed his final hole to miss out on a play-off at the Irish Open, and could only manage a closing 72 when he began the final day of the Lyoness Open just two shots off the pace.
Cabrera-Bello said: “On some occasions I have been a little unfortunate, other occasions the competition is very hard and other people have just outplayed me, and other times I have made some mistakes, which I have learned from.
“Hopefully I put the pieces together this week, we will see.”
BMW International Open leaderboard (after Round Two):
-12 R Cabrera Bello (Esp)
-11 J Morrison (Eng)
-10 L Jensen (Den), M Hoey (NI)
-9 T Jaidee (Tha)
-8 P Larrazabal (Esp), C Paisley (Eng), A Canizares (Esp)
-7 P Lawrie (Ire), B Dredge (Wal), P Hanson (Swe), J Lagergren (Swe)