Cochlear implant (CI) improves hearing but communication ability still depends on several factors. The present study assesses the relation between phonological categorization ability and silent reading performance in deaf children with cochlear implant. We examine both categorical perception (CP) and boundary precision (BP) performances, two phonological variables that we analyzed together with results of silent reading. We compared 22 implanted children to 55 normal-hearing children using different age factors. The results showed that the development of voicing perception in CI children is similar to that in normal-hearing controls with the same auditory experience. This suggests a delay and not a deficit of voicing categorization, as opposed to place. Perception of phonological features plays an important role in predicting reading results of implanted children. Both implanted and normal-hearing children showed similar reading performance at the same chronological age. This suggests that implanted children seek for other strategies to compensate for the lack of perceptual acuity of phonological features.