Peeter Gysels executed primarily small-scale, brightly colored landscape paintings in the style of Jan Brueghel the Elder. Little is known about his artistic training. Although Arnold Houbraken indicates that Gysels studied with Brueghel, he must have been mistaken, as Gysels was only four years old when Brueghel died in 1625. Because of the stylistic character of Gysels' work, it may well be that he trained with Brueghel's son, Jan Brueghel the Younger (1601-1678), who also painted in the style of his father. The artist's only documented apprenticeship is with the unknown Antwerp painter Jan Boots, with whom Gysels studied in 1641. Gysels became a master in the Saint Luke's Guild in Antwerp in 1648. He married Joanna Huybrecht on 13 November 1650, with whom he had six children. One of his sons, Peeter, may have been the artist named Gysels who executed still-life paintings in the style of Frans Snyders (1579-1657) and Jan Fyt (1611-1661).
[This is the artist's biography published in the NGA Systematic Catalogue]
 Arnold Houbraken, De groote schouburgh der Nederlantsche konstschilders en schilderessen, 3 vols., The Hague, 1753: 3:53 (reprint Amsterdam, 1976).
Houbraken, Arnold. De Groote Schouburgh der Nederlantsche Konstschilders en Schilderessen. 3 vols. in 1. The Hague, 1753 (Reprint: Amsterdam, 1976): 3:53.
Wheelock, Arthur K., Jr. Flemish Paintings of the Seventeenth Century. The Collections of the National Gallery of Art Systematic Catalogue. Washington, D.C., 2005: 116.