Mr. Jones had petitioned the court to stop his execution on the ground that the inmate in the March 25 incident, Pedro Medina, suffered horribly.

Marty McClain, the litigation director for Capital Collateral Representative, which represents death row inmates like Mr. Jones, said that he planned to present witnesses who would testify that Mr. Medina was taking spasmodic breaths, with his chest heaving, when the flames erupted. Mr. McClain said this indicated that Mr. Medina's brain was functioning and that he felt pain.

''We hope to show that the State of Florida is deliberately indifferent to pain,'' Mr. McClain said. ''The way that the death penalty is administered in Florida is cruel and unusual, and we would like the court to recognize that and say that this chair cannot be used. I understand that cruel and unusual punishment may be popular with the public and legislators, but the Constitution precludes that.''

A report by the office of Gov. Lawton Chiles after the March 25 incident said that the 2,400 volts that killed Mr. Medina did so instantly, before the flames appeared, and that he had not suffered from the flames. An investigation by the Florida Department of Corrections found that the flames were caused by a corroded copper screen in the headpiece.

But a report prepared for the Governor by two engineers and made public on Friday concluded that the accident occurred because one of the sponges placed under the headpiece, used to offset the heat generated by the electricity, was dry and caught fire.