In the period 1956 - 1965 Frenken made abstract paintings with his own distinct handwriting. Best known are his "script paintings" with large letter-like figures, his "scratch paintings" with geometric figures scratched into dark paint, and his reliefs. As a young artist, he received the Royal Grant for Free Painting (1956), the Thérèse van Duyl-Schwartze Prize (1957), the Prix de Rome (1957) for painting and the Cultural Prize of the Province of North Brabant (1962).
In 1965, Jacques Frenken began sawing and assembling discarded statues of saints into Pop-Art-like sculptures and became nationally known. The saint statues he sawed into pieces and arranged into new sculptures earned him the scandalous name "Antichrist". The VPRO commissioned a documentary film about Jacques Frenken and his work in 1967. His work was exhibited and purchased by several museums in the Netherlands, and in 2017 a high-profile retrospective "Verspijkerd en Verzaagd" of his work from this period was on view at the Noordbrabants Museum in Den Bosch.
In the early 1970s, Frenken created spatial work, particularly life-size still lifes. Cupboards, ironing boards and easels, were wrapped in linen and painted in light colors. "It was about transforming reality into something spiritual. As a logical follow-up to the statues of saints: I made those profane. While I sublimated an ordinary household cupboard, by painting it white."
The quest for sublimity continued in large white paintings, from the mid-1970s, on which Frenken drew minute lines with pencil. "Penalty work", Frenken called those canvases. "I wasn't allowed to paint freely. Linear work, steady hand, and little color. I didn't have to think about it, as it were. No artistic problems, so your mind could be completely empty. A period of what you call: stillness and purification. It was really meant to lose old thoughts." In March 1979, around his 50th birthday, this got Frenken a major exhibition at Het Kruithuis in Den Bosch.
From 1980 to 1984 Frenken made large spatial works of painted paper. The Museum de Commanderie van de Sint-Jan in Nijmegen, today's Museum Valkhof, exhibited this work in 1985. From 1982 to about 1985 he worked a lot with oil crayon on thick paper.
From 1968 to 1988, Jacques taught free painting at the Art Academy of Den Bosch.
From 1983 to about 1997, Jacques Frenken experienced another very prolific period, painting expressive canvases of enormous size, sometimes longer than 8 meters, inspired by classical music. From the jumble of hellish colors, the names of famous classical composers and their compositions can be discerned.
Starting in 1997, he began to paint religious themes again. First church interiors - altars, organs, monstrances and confessionals piled or stretched into towers - then exteriors. "That has nothing to do with religion, it's just architecture. The aesthetic admiration for church architecture. That's all there is to it."
In 1998, Frenken was given a very extensive retrospective at the Museum Schloss Moyland, in Germany, 50 km east of Arnhem.
Until his death, Frenken continued to actively paint and experiment. The work he painted is unique; it resembles nothing and no one else's. In his very different stylistic periods he made work that still looks fresh, is current, original, but at the same time is a reflection of the time in which it was made.