The kindergarten teacher, Wang Yun, was arrested last year when children at the school in Jiaozuo city, eastern China, were rushed to hospital after eating their morning porridge.
The court claimed Wang had laced sodium nitrite into their breakfast as revenge for a fallout with a colleague. They had reportedly argued over student management issues.
The incident on 27 March 2019 shocked China and attracted international attention.
The young victims had all eaten the porridge which was usually served sweet. One parent told Beijing News: “The kids said the porridge tasted salty.”
The nursery school children, usually aged between three and six-years-old in China, were taken to hospital when they started vomiting and fainting.
Initial reports in 2019 claimed that the head of kindergarten had called one parent and informed him that his four-year-old daughter had fallen ill after eating the porridge.
When the father arrived, he reportedly found his daughter and other students unconscious.
Most were discharged soon after arriving in hospital while a number were kept in for monitoring with severe symptoms. One parent told Beijing News that their child had their stomach pumped.
After a 10 month stay in hospital, one child died in January.
The teacher was sentenced to death and deprived of all political rights for life on Monday at the local court in China’s Henan province.
The court called Ms Wang “despicable and vicious, and the consequences of her crimes were extremely serious, and she deserves to be severely punished.”
Sodium nitrite is largely used as a food addictive for curing meat. If overexposed to it, the substance can be toxic and possibly fatal.
The court said Ms Wang knew the nitrite was deadly and deliberately attempted to conceal her crime. The incident greatly worried local people.
This was not the first time Ms Wang had used poison. In an incident prior, the teacher had purchased nitrite online and laced the food of her husband who suffered minor injuries.
There have been other instances of schoolchildren in China being targeted with sometimes fatal attacks by people bearing grudges or the mentally ill.
In 2002, 42 people in the eastern city of Nanjing, mostly schoolchildren, died after eating snacks administered with rat poison.
The killer was sentenced to death and executed.