The gadgets reach temperatures of 220C - nearly as hot as the highest setting on a domestic oven - but they take 40 minutes to cool down.
Children then touch or pick up the straighteners if left lying around and suffer devastating burns.
The Royal Society for the Prevention of Accidents said at one hospital, one in 10 of children admitted with burns had been injured by hair straighteners.
Youngsters who grab or fall on them can suffer disfiguring injuries as their skin is up to 15 times thinner than adults.
Figures from the Royal Belfast for Sick Children show that 17 children aged between three months and nine years attended A&E at the hospital in 2009-10 with hair straightener burns. The average age of the patient was just 18 months.
They represented nine per cent of the 187 children who attended with 'thermal injuries' during that year. In June this year, the Frenchay Hospital in Bristol revealed it had treated 110 children for serious burns in the last five years.
Children are most likely to receive burns to their hands, however children have also sustained injuries to the head, arm and foot.
RoSPA has now launched a 'Too Hot to Handle Campaign' to raise awareness of the risks.
Sheila Merrill, RoSPA's public health adviser, said: "We know from reports and from talking to the people who work in A&E that burns from hair straighteners is a significant issue and a
"And yet the risks posed are so easy to reduce. Simply by putting these devices into heat resistant bags after use, and storing them in a place that's out of the sight and reach of children, we can go a long way to preventing the kind of burns which can scar for life."
Phil Buckle, director general at the Electrical Safety Council, said: "The ESC is delighted to support the Too Hot to Handle campaign.
"Electrical goods are now common items in people's homes, so it is essential that they understand the risks associated with products like hair straighteners, particularly when they are using them around children.
"By taking the simple steps suggested in the campaign, people will be able to protect themselves and their families."