MR Richard Allen is believed to have received at least $6 million upon his resignation from the Provisional Airport Authority (PAA) last Thursday.
Although the Government has remained tight-lipped on the size of the golden handshake, legislators are prepared to press for an answer from officials during an urgent meeting of the Legislative Council's ad hoc group on airport finance on Friday.
It is understood that Mr Allen, who joined the airport body in February 1991, had a package of salary, perks and gratuities worth about $4 million a year.
His contract was said to have extended until well beyond 1997.
Legislator Mr Albert Chan Wai-yip, from the United Democrats of Hongkong, said the Government should disclose the amount of the golden handshake, which was ultimately paid by taxpayers.
Mr Chan said he would like to know how the Government had come up with the sum.