Seoul - Pope Francis was due to beatify 124 Korean martyrs on Saturday who were killed in the 18th and 19th centuries, the biggest event of his five-day trip to East Asia.
Beatification is the third of four levels of recognition by the Catholic Church that culminate in sainthood.
Up to 1 million people were expected to attend the ceremony in downtown Seoul. Francis was being led through the crowds in a parade in an open-topped automobile, from which he could be seen saluting and blessing the faithful.
Earlier in the morning, Francis baptized a man who decided to convert to Catholicism after losing his son in a major ferry disaster in April. The pontiff met him and other people campaigning for an independent investigation into the accident on Friday.
The pope was also slated to visit a large Catholic-run centre in Eumseong, about 100 kilometres south-east of Seoul.