Campbell is a free agent after leaving Arsenal at the end of last season and has been sounded out by Bruce, who also retains an interest in Schalke's Heiko Westermann, Ghana international John Mensah and West Ham star Matthew Upson.
"I have known Sol Campbell for a lot of years and it was nice to see him," said Bruce. "We had a catch up to see what his ideas are and what he is up to.
"It was pretty positive stuff and we will see what happens there."
Westermann is still a primary target with a bid lodged for a player who would have been in the Germany squad had he not broken a foot in a warm-up game.
"I've a number of irons in the fire," Bruce added in the Sunderland Echo.
"The situation with Westermann was complicated because the boy got injured at the end of last season.
"But there is still interest there. We have made a bid but that hasn't come to anything at the moment."
Mensah is another under consideration. The 27-year-old spent last season on loan at the Stadium of Light from Lyon and impressed hugely when fit.
However his long-standing injury problems make a permanent move a non-starter unless Bruce can broker a pay-as-you-play deal.
"As for John Mensah, we all saw what a terrific player he is when he was here last season. When he is fit, he is up there with the best I have worked with," he said. "He has been back here to see me this week and we will have to see how that situation develops.
"Everyone knows the issue he has with his injury and he got through the World Cup hardly training and with a physio round the clock.
"With his injury issue, I don't think I could commit this club to a permanent move for John.
"I would love to bring him back, but the deal would have to be right."