General counsel Mark Harding is also leaving the bank.
The resignations come just days after it emerged the authorities are investigating a 2008 fundraising in Qatar, though sources close to the bank insist the retirements are not linked to the probe.
And on Friday chief Antony Jenkins said he will not take a bonus for 2012 as penance for the bank’s PPI, Libor and interest rate swaps crises of recent years.
Lucas has been on the board since 2007 while Harding joined as general counsel 10 years ago.
The search has begun for a new finance director and Lucas will stay in post until a successor is found – which could take up to a year.
He received almost £4m in 2010 and in 2011 in salary, bonus and long-term incentives, though he is not expected to get a large payoff on retirement.
“Chris and Mark have given tremendous service to Barclays,” said Jenkins. “The chairman, the board and all my executive committee colleagues and I shall be very sorry to see them go.”
The departure of the two executives means that Jenkins can start to put a brand new team in place.
In a few days he is going to announce details of a new five to ten year strategy for the bank, which will focus on making Barclays a “go-to” bank for retail customers.
Lucas, who has suffered from ill health, joined the bank from PriceWaterhouseCoopers.