Veteran CPI leader J Chitharanjan died at a hospital in Thiruvananthapuram late on Friday night, party sources said on Saturday.
He was 81 and is survived by wife and three children.
A former president of CPI's Trade Union wing AITUC, Chitharanjan had a stint as Minister in the state and was a member of the Rajya Sabha.
Chithranjan entered politics as a student leader in 1940s and played a key role in forming the pro-Left Travancore Students Union.
On joining Communist Party in 1944, he was assigned to organise workers in Kollam, which was then a flourishing industrial town with a number of cashew and marine product factories.
He later built unions in other sectors like transport, electricity and manufacturing industries.
A gifted Parliamentarian, he was elected to Kerala Assembly in 1977, 1980 and 1987 from Chathannur and Punalur segments in Kollam, his home district. He was a member of Rajya Sabha from 1997 to 2003.
He had served in central secretariat of the CPI and Chairman of the party's control commission.
Chief Minister V S Achuthanandan, CPI state secretary Veliyam Bhargabvan and leaders of various parties condoled his death.