Organic nanostructured materials have been extensively studied and have potential applications in the field of nanotechnology and nanoelectronics. Due to the weak bonding between their molecules, these materials are either semiconductors or insulators and therefore have wide applications in sensors and optoelectronic devices. Cost effective production can be achieved using simple deposition techniques for the device fabrication based on these materials. In this present research work we report the characterization of graphene and its nanocomposite based thin films and their fabrication in surface-type humidity, gas, pressure, temperature sensors and rectifying Schottky junctions. Graphene (G), graphene/silver nanoparticles (G-AgNps) and graphene/silver nanoparticles/PMMA (G-AgNps-PMMA) nanocomposites were synthesized and investigated as active layer in multifunctional sensors and Schottky junctions. Thin film of the nanocomposites was deposited on various substrates (glass, plastic and n-Si) using the drop casting technique. The synthesized thin films were studied using various characterization techniques such as Ultraviolet–visible (UV-Vis) spectroscopy, Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD), Energy-dispersive X-ray spectroscopy (EDX), Raman spectroscopy and Fourier-transform Infrared spectroscopy (FTIR). The band gap values of the materials were evaluated from the UV-Vis spectroscopy data. For sensors fabrication, comb type interdigitated copper electrodes of 50 μm gap were thermally evaporated on clean insulated plastic substrate. Thin film of the graphene and its nanocomposites was deposited on the surface of the pre-deposited interdigitated metallic electrodes using the drop casting method. Initially, various humidity sensing parameters such as capacitance, resistance, response and recovery time and repeatability of the surface type Cu/G/Cu, Cu/G-AgNps/Cu and Cu/G-AgNps-PMMA/Cu humidity sensors was investigated under controlled relative humidity level from 30% to 100% RH. Apparent increase in capacitance (100-10,000 nF) with the increase in the humidity percentage (30-95 % RH) at lower frequencies for both the sensors was recorded using LCR meter (GW Instek817). Resistance of the sensors dropped to zero as the humidity level is increased from 30 to 95 % RH in the chamber. The devices were tested for real time stability and for fast response/recovery time. Both the devices showed an excellent stability and response by recording their resistance and capacitance respectively. A lagging of RH decreasing response from RH increasing response was observed at 500 Hz frequency for both the sensors depicted from the hysteresis curve. The gas sensing properties of the fabricated device was recorded at various concentrations of gases in the range of 0 to 6000 ppm. The sensor was exposed to three different gases i-e ammonia, ethanol and methanol and the change in electrical properties of the fabricated sample devices were measured by LCR meter (GW Instek817) at various frequencies. The sensors showed a good sensitivity, small response/recovery times and better selectivity towards the testing gases. It was observed that sensors were about 3 times more sensitive to ammonia as compared to other two gases. The relative capacitance was increased by 7000, 6000 and 1240.8 times at 100 Hz for RGO-AgNps, RGO-AgNps-PMMA and RGO thin film sensor, respectively, when exposed to the gas atmospheres. These experimental obtained results showed that RGO-AgNps nanocomposite-based sensor showed better response as compared to the other two fabricated sensors. The capacitive/resistive response for every 10-degree increment in the temperature of the testing chamber was presented to measure the temperature sensing characteristics of the fabricated devices. For the pressure sensing, a self-made setup was used using weights from 1 gm to 500 gm. The experiments were performed at controlled temperature and totally isolated environment. The capacitance of the devices, however, increased with the increase in the applied pressure. The response and recovery time calculated for the piezo-resistance was 12.5 s and 14.6 s (on average), respectively. The sensors were also tested for very low-pressure regime such as human touch and the response time was 20.5 s, 20.1 and 19.5 s and the recovery time was 25.3 s, 25 s and 24.6 s for G, G-Ag and G-Ag-PMMA nanocomposite thin films, respectively. The DC electrical characteristics of Al/G /n-Si, Al/G-AgNps/n-Si and Al/G-AgNps-PMMA/n-Si Schottky diodes were studied at room temperature. The current – voltage ( ) characteristic of the fabricated junction showed a rectifying behaviour. The junction parameters for all the three devices such as ideality factor (n), series resistance (Rs), and barrier height ) has been extracted, using various methods, from the experimentally obtained data and compared with each other. The frequency dependent analysis of the dielectric properties was performed by using impedance spectroscopy for the active materials. The micro structural and electrical properties were evaluated by plotting the complex impedance, complex modulus and conductivity plots for G, G-AgNps and G-AgNps-PMMA nanocomposites.