Molecular semiconductors based on charge transfer complexes of tetracyanoethylene (TCNE) with phenothiazines namely phenothiazine, 2-chlorophenothiazine, 2-acetylphenothiazine and 2-(trifluoro)methylphenothiazine have been prepared and characterized by elemental analysis, thermal, spectral and X-ray diffraction methods. The thermal decomposition behavior of these materials indicates that they are thermally stable up to about 100-degrees-C and then proceed to stoichiometric (1:1) weight losses corresponding to TCNE and phenothiazines. The stoichiometries were confirmed further from the combustion data. The existence of radical cations of phenothiazines and radical anions of TCNE were confirmed from their electronic and infrared spectral data. The preferential complexation with H-intra form of phenothiazines were indicated by their H-1 NMR spectra. These materials were polycrystalline in nature and the powder X-ray diffraction data give their structures to be orthorhombic. The electrical conductivities are rather low but they obey the characteristic molecular semiconductor behavior with two activation energies indicating mixed conduction behavior. The magnetic measurements indicate that these materials are diamagnetic in nature.