Manager Pep Guardiola is keen to strengthen his defensive options and has taken a shining to Cahill after his consistent performances over the last two years.
The 25-year-old is now a regular in the England setup and was the subject of intense transfer speculation over the summer with Arsenal and Tottenham chasing his signature.
Both failed with £10 million bids as the Trotters stood firm over their valuation but they would be hard-pressed to deny Cahill a move to the European champions.
However, with his current deal at the Reebok Stadium running out at the end of the season, Cahill would be free to discuss a move with other clubs and the La Liga giants are considering bringing him in to strengthen their back line.
Injury to skipper Carlos Puyol has forced Guardiola to partner midfielders Sergio Busquets or Javier Mascherano with Gerard Pique in the heart of defence.
The Spanish coach is concerned that his team will be vulnerable at set pieces without a defender who is dominant in the air and has identified Cahill to provide some aerial strength.
Owen Coyle will face a monumental task to try and keep him if Barcelona formally indicate their interest, with Cahill desperate to cement his position as an England starter.