Digraphs are two letters written together to represent one sound. English is full of these (e.g., 'th', 'sh', etc.), but there are only two in Kryptonian as follows.

In Kryptonian, all of the voiced stops, affricates, and fricatives (the bottom three spokes of the written alphabet) can be prenasalized. In writing, this is indicated by preceding the consonant's letter with the : character. This character has no pronunciation on its own, but coarticulates with the following consonant to create a syllabic nasal continuant. This is only found at the beginning of root morphemes.