Toos Kray learned her skills from her father Hein Kray, who painted his entire life in Assen and surroundings. Later on she followed lectures of Peter Boekholt, Sjoertje Hak, Treintje Muis and Frans van Lingen.
The main source of inspiration for Toos, was nature. Her subjects are flowers, trees in the woods, but also characteristic farm yards, picturesque spots in villages and cities. Toos preferred to paint outside, at location. Sometimes abroad.