Kwok, 63, and Hui, 66, were found guilty Friday in a trial which has shocked the city known for clean governance.
Hui is the most senior official to be convicted of graft in Hong Kong's history, while Thomas Kwok was joint chairman of its biggest property company, Sun Hung Kai.
Their defence argued Monday morning against lengthy sentences, citing age and frailty -- including a susceptibility to cold weather.
The seven-month trial centred around a total of USD 4.38 million in payments which the prosecution said were made to Hui by Thomas and his billionaire brother Raymond to be their "eyes and ears" in government.
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Raymond was cleared of all charges and Thomas cleared of two out of the three against him.
He could face longer in prison than Kwok after being convicted on five of the eight charges against him.
In mitigation, Hui's defence read a letter of support from Hong Kong's former chief executive Donald Tsang -- who ended his term in June 2012 after admitting accepting gifts from tycoons in the form of trips on luxury yachts and private jets.
"Some of us were aware of his lavish lifestyle, but we took that as his personal choice," Tsang said.
Former pro-democracy lawmaker Lau Chin-shek backed Hui in a letter -- and added that he suffers in the cold.
"Although I have a different stance from him, I admire his abilities," said Lau.
"He is extremely vulnerable to low temperatures and has taken Chinese medicine for a long time."
The court was also read a letter from an orphan who had been sponsored by Hui and his wife, which described them as "warm-hearted people".
Kwok's British lawyer Clare Montgomery said her client was "likely to struggle physically in a prison environment", adding that his health had deteriorated in recent years.