adapted from Epicurious
Wash kumquats and slice each crosswise into thirds. Remove the seeds that are easy to get, don't worry about the others.
Bring the water and sugar to boil in a medium sized, heavy bottomed saucepan. Add the sliced kumquats and simmer until fruit is translucent and tender, about 15 minutes. Cool and transfer to a glass jar. Store covered in the fridge for a week or two.