It is not known whether Hall has taken a job elsewhere. PR manager Gail Gillogaley, who is covering Hall's role in the interim, said: 'He's left to pursue other opportunities.'
She added that a decision had not yet been made on whether Hall will be replaced.
Hall joined as head of corporate communications at Opodo in March after a stint as press and PR manager at Virgin Atlantic.
His departure coincides with that of Opodo CEO Giovanni Bisignani, who has moved to become director-general of the International Air Transport Association.
Opodo was formed earlier this year by nine European airline companies, including British Airways and Lufthansa.
It is now being run by chairman David Coltman as the CEO post remains vacant following Bisignani's departure.