The painting is a tempera on canvas, from the first quarter of the 15th century, attributed to the late Gothic painter Antonio Veneziano.

It depicts the Gospel episode of the martyrdom of St. John the Baptist, by beheading. The body of the saint - dressed in rough camel’s hair - rests on all fours on a grassy mantle, as if sagging lifeless after the executioner has removed his head. The head, fallen to the ground and seen in profile, is enhanced by a golden halo, while the upper part of the bust is in slight foreshortening, so as to reveal the section of the truncated neck and the copious gush of blood. The executioner, in a pale orange robe, stands out against a dark background, as he calmly replaces his sword in the scabbard.

Scholars speculate that this painting is a fragment of a gonfalon, or banner. The presence of St. John the Baptist, protector of the city of Florence and owner of the Baptistery, suggests the use of such a device in processions and other religious celebrations.