Despite Cu2ZnSnS4(CZTS) is a potential candidate for solar cell applications, so far, low efficiency values have been reported. In particular, for spray-deposited CZTS, efficiencies lower than 2% are commonly achieved. It is well known that one of the most important parameters governing solar cell performance is minority carrier diffusion length (Ln). In this work, CZTS thin film solar cells with different compositional ratios are fabricated in order to study its impact on Ln values. The Ln parameter is calculated for sprayed-CZTS layers using external quantum efficiency measurements in conjunction with optical absorption coefficient versus wavelength measurements - for the first time. Values in the range of 0.11-0.17 μm are obtained emphasizing the need for improving sprayed-CZTS crystalline quality.