A prison inmate in Ohio due to be put to death says he's so fat that his executioners would have trouble finding his veins and he might not be properly anaesthetised.

Lawyers for death row inmate Richard Cooey argue in a federal lawsuit that their client had poor veins when he faced execution five years ago and that the problem has been worsened by weight gain. They argue his weight could diminish the effectiveness of one of the lethal injection drugs.

41-year-old Cooey, who weights 267 pounds and is 5 feet 7 inches tall, was sentenced to die for raping and murdering two University of Akron students in 1986. His execution is scheduled for October 14. Now Cooey has filed a lawsuit based on his obesity.

Despite the bizarre nature of his lawsuit, Cooey is not the first prison inmate to cite weight as a reason to attempt to postpone his execution. In 2006, a court rejected a claim from convicted murderer Jeffrey Lundgren that he was more likely to experience pain and suffering when he was executed because he was overweight and diabetic.

In 2007, the execution of condemned Ohio prison inmate Christopher Newton sparked controversy. Newton weighed 265 pounds and, as a consequence, his veins were difficult to find. It eventually took over two hours and 10 attempts before his execution was completed. An execution normally takes just 20 minutes.