Quaternary semiconductor compound Cu2ZnSnS4 (CZTS) is a promising non-toxic absorber material for solar cells made from earth abundant elements. In this study temperature dependencies (T = 10–300 K) of current–voltage (J–V) characteristics and external quantum efficiency (EQE) spectra of CZTS monograin layer solar cells were measured in order to clarify current transport in CZTS that is still not fully understood. Three different temperature ranges can be distinguished from the temperature dependence of the series resistance (Rs) obtained from J–V measurements and the effective bandgap energy (Eg⁎) determined from the EQE spectra. Thermally activated conductivity, Mott's variable-range hopping conductivity, and very low temperature (< 40 K) blocking of the interface recombination were observed.