The average cash pay of a S&P/ASX 100 company's chief executive held steady in 2008 - a sign CEO salaries, including those of financial services firms, came out relatively unscathed from the GFC.

As the global financial crisis began in 2008 the average Top 100 company CEO in Australia saw their base pay increase 6.2 percent to $1.95 million, according to new research from the Australian Council of Superannuation Investors (ACSI).

The average cash pay of a CEO of a S&P/ASX 100 company in 2008 held steady, dropping only marginally from $3.78 million to $3.75 million.

The average annual cash bonus (for those CEOs who received a bonus) fell slightly from its record high of $2.18 million in 2007 to $1.95 million in 2008.

The average bonus in 2008 was the second highest ever recorded.

Despite the decline in average bonus levels, more S&P/ASX 100 company CEOs received a bonus in 2008 compared to 2007, with the proportion receiving a bonus increasing from 88 percent to 93 percent.

Of the five CEOs who received no bonus, two were at companies that did not operate bonus programs at all for the 2008 year and three left their companies shortly after the end of the 2008 year.

In their 2008 financial years, 13 Top 100 companies changed CEOs.

The chief executive of ACSI, Ann Byrne, said the findings underpinned the need for companies to be more forthcoming in disclosing how bonuses were determined.

"The fact that more than 90 percent of CEOs received a bonus in 2008 begs the question just how boards decide whether or not pay bonuses - it appears easier for a CEO to get fired than to receive no bonus," comments Ann.

"Additionally the Corporations Act required companies to provide a detailed summary of performance conditions for senior executive pay but most companies provided vague disclosure that did not give any information on how pay was linked to performance. In the absence of such disclosure it is hard to avoid the conclusion that at many companies a portion of CEO bonuses is not at risk," she said.

Average total pay, including the disclosed value of share based payments, fell in the 2008 year, from $5.53 million to $5.15 million (in 2006 it was $4.56 million).

Most of the decline in the average was driven by highly paid CEOs in the 2007 survey having left their underperforming companies.

Three of the Top 10 highest paid CEOs in the 2007 ACSI study departed their roles in 2008 and were replaced in the Top 10 by lower paid individuals. The three departing CEOs were Phil Green of Babcock & Brown, Paul Anthony of AGL Energy and Telstra's former CEO, Sol Trujillo.

The exclusion of Phil Green from the 2008 sample accounted for two-thirds of the decline in the average, given his disclosed pay for 2007 of $22.1 million.

ACSI's Byrne said that the study showed that companies freezing executive salaries and reducing bonuses were doing so from very high levels of existing remuneration.