Katz's paintings are divided almost equally into the genres of portraiture and landscape. Since the 1960s he has painted views of New York (especially his immediate surroundings in Soho) and landscapes of Maine, where he spends several months every year, as well as portraits of family members, artists, writers and New York society protagonists. His paintings are defined by their flatness of colour and form, their economy of line, and their cool but seductive emotional detachment. A key source of inspiration is the woodcuts produced by Japanese artist Kitagawa Utamaro.