Hierro has been playing his football in Qatar for the past year and is a good friend of the current Bolton midfielder Ivan Campo following their days together at the Bernabeu earlier on in the decade.
The former Spanish international Hierro, who won an astonishing 89 caps is set to be put through his paces next week as Allardyce looks to add further faces to his defensive options to add to that of Tunisian stopper Radhi Jaidi who moved to the club earlier on this week.
With Emerson Thome looking increasingly unlikely to sign a new deal and the fact that Steve Howey has left the club Allardyce knows all too well that he needs some experienced defensive cover, could Hierro be what he is looking for?
"We'll probably get him over next week and have a good look at him" the Bolton boss confirmed.