Along with eight members of Catalonia's Cabinet Jordi Cuixart, head of Omnium Cultural and Jordi Sanchez, the president of the Catalan National Assembly, are also due to appear.
Sacked regional vice-president Oriol Junqueras, one of his ERC party's main candidates for the election, has asked to be allowed to leave jail in order to campaign in the vote which was called by Madrid.
Mr Junqueras and seven other former members of the Catalan regional cabinet were jailed on November 2 pending trial on charges of sedition, rebellion and misappropriation of funds after the Catalan government declared independence from Spain.
AFP/GettyOriol Junqueras (far right) is appearing at the Supreme Court today
The referendum vote was declared illegal by Prime Minister Mariano Rajoy’s administration and the security forces - the national police and Guardia Civil took violent action in an attempt to stop people trying to vote, often using plastic bullets and batons in their attempts to close down polling stations.
The Catalan government, led by Carles Puigdemont, then declared independence with Mr Rajoy reacting by invoking Article 155 of the Spanish constitution and imposing direct rule over the wealthy north-east region.
The eight jailed cabinet members, whose original hearing was at the Spanish High Court, had their case moved to the Supreme Court after the presiding judge argued the different Catalan cases should be tried in the same court.