El Hadary is playing at his seventh finals, one shy of the record held by Rigobert Song of Cameroon, and is expected to start for Egypt when they play Mali in their opening Group D game in Port Gentil on Tuesday.
If he does line up, El Hadary will shatter the record set by compatriot Hossam Hassan in 2006, when the feisty striker was 39 years, five months and 24 days old in his last game at the finals.
The veteran goalkeeper had been recalled to Egypt's squad as back-up last year but promoted up the order and was first choice for their two World Cup group qualifiers against Congo and Ghana in October and November -- matches they both won.
However, his place has not been confirmed in the build-up to Tuesday's match, which will be Egypt's first in the finals of the tournament since 2010.
"We haven't chosen our first choice keeper yet," goalkeeper coach Ahmed Nagy told Egyptian television at the weekend.
"Having three excellent and experienced goalkeepers in the current squad gives Egypt a good boost in Gabon," he added.
El Hadary was a squad member when Egypt won the Nations Cup in Burkina Faso in 1998 and again sat on the bench in 2000. He played at the 2002 finals and again from 2006 to 2010, when Egypt won three back-to-back titles.
He has also made no secret of his desire to compete at the World Cup in some 18 months time.
"I will fight to reach the World Cup," he told reporters. "I don't care about my age; I train like I am 20 years old."
Greek international Giorgis Koudas, brought on as a substitute in a friendly against Yugoslavia in 1995 aged 48, is the oldest international according to the statistical site rsssf.com.
(Editing by John O'Brien)
