Commonwealth Bank chief executive Matt Comyn has spoken face-to-face with customers affected by the kind of misconduct revealed at the banking royal commission.

Mr Comyn, who took up the top job six months ago, has revealed the fact while being grilled by federal politicians at a parliamentary hearing in Canberra.

It came after he acknowledged the hurt the bank's actions have caused some Australians.

"I certainly acknowledge the hurt and the very, very difficult circumstances that some of our customers have found themselves in, and some of that as a result of our actions," he said on Thursday.

The chief executive said there is no substitute for hearing those people's stories directly, and he's spoken with a number of them over the phone and fewer than 10 of them in person.

"To get a proper understanding of the individual cases, some of them are very, very complex and they do take quite a bit of time," he said.

So far this year, 41 Commonwealth Bank employees have been terminated due to misconduct, while another nine have resigned while being investigated, Mr Comyn said.

He could not confirm how many of the sackings were directly linked to revelations at the royal commission.

Mr Comyn earlier admitted the Commonwealth Bank was too slow to fix customer service problems uncovered by the banking royal commission because it had become complacent.

"There have unfortunately been failures of judgment, failures of process, failures of leadership, and in some instances, greed," he said.

"We've been too slow to identify problems, too slow to fix underlying issues, and too slow to put things right for customers.

"We became complacent."

Mr Comyn laid out the steps the bank has taken, including strengthening its lending processes and making it simpler for customers to choose products.

But he expects Australians will be sceptical and the bank has plenty of work to do to regain trust, and will be judged on its actions.

The hearing is being held by the House of Representatives committee on economics as part of a review into the big four banks.

It comes less than two weeks after banking royal commissioner Kenneth Hayne QC delivered an interim report, blaming greed and the pursuit of profit for the widespread misconduct in the banking and financial services industries.

The Commonwealth Bank, ANZ, National Australia Bank and Westpac have all pledged to mitigate their failures.

Westpac CEO Brian Hartzer will also front the hearing on Thursday, which is the first of three being held in the coming week.

ANZ chief executive Shayne Elliott will appear on Friday and National Australia Bank boss Andrew Thorburn will appear next week.