The High Court ruled last year that Morrisons was liable for the release of information and its employees were entitled to compensation.
The case is the first data leak class action in the UK.
The proceedings are due to take place on Tuesday.
The Supermarkets appeal has significant implications for other organisations, who could also be found liable to pay compensation for the acts of rogue employees.
Falanx Group Limited (LON:FLX), is a global intelligence and cyber defence provider working with blue chip and government clients. It operates the MidGARD cyber monitoring platform for corporate and governmental customers which utilises a combination of proprietary and third-party processes and technologies