We identified the chaperone DNAJC30 as an important factor to maintain NADH:ubiquinone oxidoreductase (complex I) activity. In this complexome analysis we detected DNAJC30 in substoichiometric amounts attached to respiratory supercomplexes (I/III2/IVn and demonstrate an accumulation of complex I containing respiratory supercomplexes in the patient cell line with DNAJC30 mutations compared to the control cell line.