Thin films of 1,6,7,12-tetrachloro-N,N′-dimethylperylene-3,4,9,10-biscarboximide (Cl4MePTCDI) prepared by physical vapor deposition (PVD) were compared to thin films of the unchlorinated N,N′-dimethylperylene-3,4,9,10-biscarboximide (MePTCDI) to investigate the influence of a changed molecular structure on the electrical properties of the materials. The films were prepared on microstructured Si/SiO2 substrates with interdigitated Au electrode arrays of 2 μm electrode distance or on quartz glass with electrode distances in the mm range. The films were investigated by conductance measurements, thermoelectric power, electric field effect, ultraviolet photoelectron spectroscopy (UPS) and atomic force microscopy (AFM). The thickness-dependence of the conductance measured during film growth (in situ) indicated a growth mode in islands (Volmer-Weber), which was confirmed by subsequent AFM. As expected, Cl4MePTCDI was characterized as an organic n-type semiconductor. Charge transport occurred by a hopping mechanism as revealed by temperature-dependent thermopower and field-effect measurements. Effective electron mobilities at room temperature were found around 10−5 cm2 V −1 s−1 considerably lower than the values for MePTCDI. A rather constant concentration of mobile electrons of (1–2) × 1018 cm−3 was determined for both materials. The morphology of Cl4MePTCDI islands indicated amorphous growth as opposed to crystals obtained for MePTCDI, as also revealed earlier by optical spectroscopy and the role of crystallinity in the electrical conduction is discussed.