Abstract: Fast positive photoresist compositions employing cresol-formaldehyde novolak resins made from a mixture containing meta- and paracresol or ortho-, meta- and paracresol in a ratio selected from a given range and one or more of a selected group of naphthoquinone diazide sensitizing compounds. When dissolved in a mixture of organic solvents, the photoresist compositions are suitable for application as a thin coating to a substrate. After the coating has been dried, the coated substrate can be exposed to image-wise modulated actinic radiation even in the deep ultra-violet range and developed in alkaline solution, yielding a high-resolution relief pattern of resist on substrate useful for a number of applications.