Former Blue Peter presenter John Noakes has been reported missing from his home in Majorca.
Local police in Andratx said they were alerted by the 81-year-old's wife Vicky at around 8am on what is Spain's hottest day so far this year.
Officers from the local police and the Civil Guard are taking part in the search, with volunteers expected to join in this afternoon.
Mr Noakes, who is Blue Peter's longest-serving presenter, suffers from Alzheimer's disease, local police said.
He was wearing blue shorts and a blue and white top when he went missing.
An Andratx local police officer said: "We are searching for Mr Noakes in the village.
"His wife reported him missing this morning. She is worried because of his state of health and the heat, which is around 35C (95F) today."
The former presenter worked on Blue Peter for 12 years and six months in the 1960s and 1970s.
Andratx town hall put two pictures of Mr Noakes on its Facebook page.
A message read: "We asking for the public's help to find this missing man.
"He was wearing light blue shorts and a white and blue shirt. He is 81."