Remove the husks and silks and boil the corn on the cob in enough water to cover for 5 minutes. Reserve the cooking water, remove the corn cobs and run the cobs under cold water to cool.
Carefully remove the corn kernels from the cobs with a sharp knife and use the kernels for another dish. Return the cobs to the pan of water and boil for 30 mins.
Stir in the pectin and bring to the boil. Add the sugar and simmer for 5 minutes. Skim off and discard any foam with a spoon. Carefully pour into a sterilized jar and allow to cool, then refrigerate.