According to Robert H. Kirschner, the deputy chief medical examiner of Cook County, Illinois, "The brain appears cooked in most cases."
According to Judge Brennan, the prisoner's eyeballs sometimes pop out and rest on his cheeks. The prisoner often defecates, urinates, and vomits blood and drool. The body turns bright red as its temperature rises, and the prisoner's flesh swells and his skin stretches to the point of breaking. Sometimes the prisoner catches on fire, particularly if he perspires excessively. Witnesses hear a loud and sustained sound like bacon frying, and the sickly sweet smell of burning flesh permeates the chamber.
There is some debate about what the electrocuted prisoner experiences before he dies, many doctors believe that he feels himself being burned to death and suffocating, since the shock causes respiratory paralysis as well as cardiac arrest. According to Harold Hillman, "It must feel very similar to the medieval trial by ordeal of being dropped in boiling oil." Because the energy of the shock paralyses the prisoner's muscles, he cannot cry out. "My mouth tasted like cold peanut butter. I felt a burning in my head and my left leg, and I jumped against the straps," according to Willie Francis, a 17-year-old who survived his execution in 1946. Francis was successfully executed a year later.

When things go wrong.
Though all methods of execution can be botched, electrocutions go wrong frequently and dramatically, in part because the equipment in most states is old and hard to repair. At least five have gone awry since 1983. A particularly appalling instance of this took place on the May 4th 1990, in the case of Jesse Joseph Tafero in Florida. According to witnesses, when the executioner flipped the switch, flames and smoke came out of from around the helmet and mask on Tafero's head. Twelve-inch blue and orange flames sprouted from both sides of the mask. The power was stopped, and Tafero took several deep breaths. The superintendent ordered the executioner to halt the current, then try it again. And again. The helmet used artificial sponge (which was initially blamed for the problem) because it is uniformly conductive as it has a uniform thickness. The subsequent enquiry found that the solder joint on the head electrode had separated causing a major high resistance connection. This was proved in court by the two burns on Mr. Tafaro's head. The electrodes had not been checked but this was “hushed up” by the state. According to the state prison medical director, Frank Kligo, who attended Tafero’s execution, it was "less than aesthetically attractive."

Another electrocution in Florida went seriously wrong in 1997 when Pedro Medina was executed on March 25th. Witnesses saw a blue and orange flame shoot 6-10 inches out of the helmet covering Medina's head. It burned for about 10 seconds, filling the chamber with acrid smoke and the smell of burning flesh.
An investigation by prison officials blamed the flare-up on a corroded brass screen used in the helmet.
Michael Morse and Jay Wiechart, both experienced in electric chair design and operation, blamed the malfunction on a dry sponge used in conjunction with a wet sponge in the helmet.
Electrocution was challenged through the Florida courts, by death row inmate Leo Jones as a "cruel and unusual" punishment, something which is of course banned under the Constitution.

However a Florida Supreme Court hearing ruled by 3 to 1 on October 21st 1997 that it use did not constitute cruel or unusual punishment.
Yet another electrocution in Florida seemed to be botched when Allen Lee "Tiny" Davis was executed for murder on July 9th 1999.
Blood appeared to ooze from Davis' nose and mouth as he was hit with 2,300 volts at 7:10 a.m. The governor's office said it was simply a nosebleed. The official photographs of the execution seem to bear this out and are not suitable for those of a squeamish disposition.
By the time Davis was pronounced dead five minutes later, there was blood on the collar of his white shirt, and the blood on his chest had spread to about the size of a dinner plate, even oozing through the buckle holes on the leather chest strap holding him to the chair.

"Nothing went wrong," said Cory Tilley, a spokesman for Gov. Jeb Bush. "The chair functioned as it was designed to function and we're comfortable that that worked." Tilley said that despite how things seemed to witnesses of the execution, there was no blood from the mouth or chest.
"The only source of blood was from the nose. He had a nosebleed. Why that was will be in the autopsy." Tilley said there was some speculation the nosebleed was caused by Davis' high blood pressure.
The photographs of the execution showed "distinct signs of pain," according to Dr. Donald Price, a neuro-physiologist, who was commenting upon Davis' half-shut eyes, scrunched-up nose and bruises on his face.

A physicist who specializes in the effects of electricity testified that it was possible for an inmate to remain conscious more than 15 to 30 seconds into the execution.
"It's my opinion that death is not instantaneous and make take several minutes," said Dr. John Wikswo of Vanderbilt University in Nashville, Tennessee.
The autopsy report said Davis had "several predisposing risk factors" for nosebleeds, including hypertension and arthritis that required him to take blood-thinners.
Florida had a new oak chair built in 1998 to replace the original one built in 1923. (see picture) Attorneys acting for Allen Lee Davis claimed that Florida Department of Corrections documents show the chair may be operating with "obsolete breakers" and outdated electrical components that it was proposed to replace in April 1999. Florida decided not to install the new parts, including leg and head electrodes, apparently due to the $265,000 cost.