The kallitype is an iron-sensitive process that uses silver to form the image. The kallitype emulsion is a mixture of ferric oxalate and silver nitrate, with the addition of either oxalic acid or potassium oxalate. When exposed to light the ferric oxalate is changed to the ferrous state, which reduces the silver nitrate to the metallic silver. When developed the ferrous oxalate is dissolved and the metallic silver is left forming the image.

The kallitype process is a very unforgiving one, great care must be taken. The resulting prints are quite similar to platinum prints, however kallitype prints are not nearly as permanent as platinum, although substantially cheaper to produce.