Jean-Henri Gruyer was born in 1734 in Dole, France in the diocese of Besançon. After having been ordained as a priest of the diocese of Saint-Claude, he entered the Congregation of the Mission in 1771.
After his first year in the intern seminary Gruyer was appointed to the house in Angers, a residence for missioners which had no other ministry. About a year later he was transferred to Versailles, where the Congregation had two parishes: Notre Dame and Saint Louis. He spent about ten years in Notre Dame and was then transferred to Saint Louis.
On 27 April 1791 the Saint Louis parish was taken over by priests who had taken the oath of fidelity to the Civil Constitution of the Clergy, which asserted that the Pope had no authority in France and provided for election of bishops and priests by panels of citizens. At that time Gruyer returned to the diocese of Besançon.
At the beginning of August 1792 Gruyer traveled to Versailles and then to Paris on the 12th or 13th. Information in a travel document of that year describes him as five feet four inches tall (162 cm). His hair was white and he was balding. He had deep-set grey-blue eyes, a round face and narrow chin. On arrival in Paris he asked for temporary accommodation in Saint-Firmin. On the 13th the government place a guard on the house, which meant that everyone inside became a prisoner.
Although it certain that Jean-Henri Gruyer was killed in the September Massacres, about his death and the deaths of most others killed in the Massacres no details are known.
Vincentian Martyrs of the French Revolution by Thomas Davitt C.M.