Payne was ill with hyperpituitarism and worked in S.T.A.R. Labs trying to come up with a cure for his illness.
One day he visited Matt Hagen the second Clayface who had the ability to remold his features, Payne was able to acquire a small tissue sample and find a temporary cure to control his metamorphosis until sometime later while with his girlfriend his skin began to melt from his body. Trying to calm his appalled companion he grabbed a hold of her and gave her his “death touch” and she began to melt as well until she was no more than a puddle of protoplasm. Soon after he manages to make a suit that won't melt to his touch to stop himself from touching anyone and killing them. Unfortunately he needs to touch people to survive which gives him a hunger sensation but still goodhearted he only kills street thugs and other street dwellers who no one would take notice of their disappearance.
As months went on he broke into many labs across the city stealing equipment to find a cure for his problem. He was then caught by Batman in one lab and fought him. Batman was able to short out Payne’s suit to which Payne retaliated by smashing the axles of Batman’s car as he made his escape. As Payne made his way back to Gotham but his sickness began to take effect and he knew he must touch someone for his “Hunger” was increasing. He stopped a man and killed him then
preceded to steal his car. As he arrived to Gotham he was greeted by Commissioner Gordon who had closed off the Bridge which made Payne climb to the top of the bridge where he was caught by Batman. They fought again until Payne threw himself into the river and was able to retreat safely to his hideout. Hours later Batman arrived and they began to battle for a third time that night, Batman tired of this fight was able to break the power pack on Payne’s suit. As Batman savored victory he noticed that they had started a fire in the fight and the hideout upsurged in flames, Batman took Payne’s unconscious body outside the building. Payne woke up to the horrid sight and ran back into the burning building for his mannequin girlfriend Helena. The woman he was in love with for she was impervious to his deadly touch.
Months later Payne found a new hideout at a department store where he had his Helena as a display mannequin and they lived happily. Payne’s happy life came to a halt when he saw that a guard for the store had on of the scarf’s that his girlfriend had displayed. Enraged with jealousy and thoughts of her unfaithfulness he killed the guard and hid the body. Much time later the body was discovered and the report found its way to Batman’s hands who knew who had done this atrocity. Batman found and confronted Payne and easily defeated him and took him to Arkham Asylum where he was able to have his mannequin girlfriend Helena in his cell with him.
As Mud Pack events begin to take place, the 4th Clayface Sondra Fuller is masked as Looker and pays Payne a visit. She used her mimic abilities to brainwash Payne into killing his mannequin girlfriend and breaking out. He was hunted by the Gotham P.D. and was subdued but Sondra used her mimic telekinetic abilities to carry his body to Basil Karlo the original Clayface hideout which is an abandoned theater.
After a while of schemes to defame and capture Batman Karlo betrays them both and takes blood samples to use for his own plans in becoming more powerful. Enraged Payne sees that he was used by Karlo and Sondra and attacks her, while about to kill her she confesses that she is sorry for using him the way she did. A big turn of events he spares her and they ultimately fall in love, Sondra soon becomes pregnant with Payne’s child and they name the boy Cassius. As his son grew he began to show signs of his parents abilities.
One day as Payne and Sondra ventured out into the wilderness for supplies Abattoir found their cave and kidnapped the child.
He left a message saying that if the wish to see their child again alive and unharmed then they will abduct Graham Etchison. They quickly returned to Gotham and encountered Batman. Batman helped them rescue his child and in a quick turn of events Batman split open Payne’s helmet cover and injects it with gas knocking Payne unconscious and sending him back to Arkham Asylum.
Payne eventually left Arkham and was secretly broken out by Prometheus. Payne was forced to work for Prometheus, when Payne's son was threatened to be killed by him. Prometheus gave Payne back his shapeshifting ability and became a decoy. The Justice League realized to late what was happening and an explosive devise was planted inside Payne's body and was detonated, presumably killing him.
Payne’s touch causes anything organic to melt into a puddle of protoplasm.
His suit gives him super strength however without it he has the same strength of a normal human.
He is super smart and graduated with honors at Hudson University which later opened the door for him to become a researcher in S.T.A.R. Labs.
In other media
Batman: Arkham Asylum
In the game Batman: Arkham Asylum, Clayface was seen while Batman searching for Arkham Warden Quincy Sharp, came across a cell behind a clear wall with no bars. His biography states it is Basil Karlo, although the presence of a mannequin in the cell are a reference to Preston Payne, who was 'married' to a mannequin he referred to as 'Helena'.
Batman: The Brave and the Bold
In the Batman: The Brave and the Bold episode "Joker: The Vile and the Villainous" a portrait of the Preston Payne version of Clayface appears in the villain bar where the bad guys hang out.