This work investigated the catalytic ability of modified cobalt-titanate nanowires (Co-TNW) on photodegradation of three antidepressants: amitriptyline (AMI), trazodone (TRA) and venlafaxine (VEN). The experiments were carried out with spiked tap water under UV-Vis radiation in the presence of Co-TNW as catalyst. The transformation products (TPs) were elucidated by ultra-high performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry. Degradation pathways were proposed and in silico toxicity assessment (ecotoxicity and mutagenicity) were performed. The results showed an enhancement in the AMI and VEN removal efficiency due to the photocatalyst use. The TRA showed a similar degradation rate in photolysis and photocatalysis. Moreover, it was verified that in the photocatalytic assisted processes, more AMI and VEN TPs were formed. Overall, the structures of twenty TPs were proposed (eight from AMI, seven from TRA and five from VEN) and to the best of found knowledge, fourteen of them have never been described before. Some of these TPs had a higher ecotoxicity than parent compound by the in silico analyses. Regarding of TRA, all TPs resulted in positive mutagenicity in at least one prediction model. Therefore, it is necessary to consider the formation of TPs in photocatalytic degradation of contaminants since they may impose toxicity to aquatic organisms.