The rare paintings were undertaken by Lambert Barnard (1485 1567) in the 16th century and feature an image of Henry VIII believed to be the only surviving secular image in Britain of the king.
Work to restore the paintings is being undertaken by the Hamilton Kerr Institute and follows the launch of a national appeal to raise £250,000 to save the paintings.
Alison Godfrey, Director of the Chichester Cathedral Restoration and Development Trust, said the work being carried out was critical and would prevent further deterioration for the present time.
She appealed to people to help raise the full amount of money needed to fund the restoration work.
So far we have managed to raise £202,000 towards the project. However, the paintings are in such a critical condition that it was not possible to wait any longer before the stabilisation could commence, she said.
We just hope that visitors, historians and art enthusiasts will now help us with this final amount that we desperately need. The paintings are completely unique, nothing like them survives in either this country or Europe.
It is our responsibility to look after them and make sure they survive for future generations.
The paintings are done on 32ft x 14ft panels and the restoration work is being undertaken within the cathedral where members of the public are able to view the conservators at work.
They represent unique examples of propaganda art and are believed to be the largest surviving paintings of their kind.
We would really like to encourage everyone who is interested to come to the cathedral, which is open every day, free of charge, and see the paintings, said Ms Godfrey.
Rupert Featherstone, from the Hamilton Kerr Institute, will give a free lecture on the paintings at the cathedral on February 14 at 6.30pm.
To donate to the appeal, visit: www.chichestercathedraltrust.org.uk/dyn/pages/chichesters-tudor-paintings Christian Today