Phenidone is used as a low toxic common photography developer. It is sparingly soluble in cold water and moderately in hot, and can require temperatures of 175°F/80°C to dissolve.

Phenidone can be substituted for metol. There is evidence that as a substitute for metol it causes true increase in film speed. However, Phenidone should not be used as a substitute in developers in which metol is the sole developing agent, such as Kodak D-23 and D-25. Try substituting approximately 10% of the amount of Phenidone for the amount of metol required.