Saudi Arabia executed 184 people last year, including three prisoners who were teenagers when they were arrested.
The grim figure is the highest number of state killings which have taken place in the Middle Eastern country in the last six years.
Among the dead was Abdulkarim al-Hawaj beheaded at 21. He had been arrested age 16 for sending WhatsApp messages about an anti-government demonstration.
He was tortured with electricity while his hands were chained above his head until he confessed.
Abdulkarim and 36 others were executed on a single day in April during a beheading bloodbath for prisoners convicted of ‘terrorism’ offences.
One was crucified and put up in display as a warning to others.
A second youngster, Mujtaba al-Sweikat, was put to death after being arrested as a 17-year-old boarding a flight to the US where he was due to begin his studies at Western Michigan University.
Campaigners say he was convicted solely on the basis of a confession extracted under torture after he was severely beaten all over his body, including the soles of his feet.
Court documents showed that Mujtaba al-Sweikat confessed to throwing Molotov cocktails at security forces and running a chat group on his Blackberry phone that helped to organise the demonstrations.
His father insisted that his son only twice joined demonstrations and for five minutes on each occasion.
“He was subjected to psychological and physical abuse which drained his strength,’ said Nader al-Sweikat.
“The interrogator dictated the confession and forced him to sign it so that the torture would stop. He signed it.”
Another of those killed was teenager Salman Qureish, who was arrested shortly after his 18th birthday accused of crimes he committed as a juvenile.
Sentencing a person to death who is under 18 is banned under international law.