The charge-transfer complex crystal of N, N dimethyl 4 amino pyridinium 4 amino benzoate dehydrate is synthesised and the complex has been confirmed by studying the spectroscopic results. The crystal structure was comprehended by single crystal X-ray diffraction analysis. The cation and anion are linked through strong hydrogen bond in the molecule. The Mulliken atomic charge and the values of electronegativity and chemical hardness index were calculated for interpreting and predicting the reactive behaviour. The lowering in the HOMO and LUMO energy gap explains the eventual charge transfer interactions that take place within the molecules. Fourier transform infrared (FT-IR) spectroscopic studies were also performed for the identification of different modes present in the compound. This dielectric study highlights the dielectric constant decreases with increase in frequency. The charge transfer crystal was subjected for its biological activity, such as antibacterial, antifungal and antioxidant activity. The antibacterial and antifungal activities of the synthesized complex were examined against various bacteria and fungi species, which exhibited a good antibacterial and antifungal activity compared with standard antibacterial and fungal species. The compound has significant antioxidant activity against free DPPH radicals.