The key concern for environmental scientists is the detection and monitoring of hazardous species such as CO using quick, cost-effective, and highly specific equipment. The present detection methods are either indirect or time consuming and costly. These sensors work at high temperatures and have a very sluggish reaction time. Nanocomposite polymeric combinations have however shown to be effective sensors for detecting dangerous gases. Nanocomposite copolymers of aniline and formaldehyde produced by chemical polymerization using Fe-Al metal complexes have been discovered to be very selective and effective CO sensors. Thin films of Fe-Al doped nanocomposite copolymer evaporated under high vacuum on diverse substrates such as mica and glass were found to have good stability, sensitivity, selectivity, and a quick response reaction to CO vapors in the air. Optimization of doping (Fe-Al) in nanocomposite copolymer during synthesis results in high stability, sensitivity, selectivity, and specificity. These sensors are designed to work at ambient temperatures. This paper describes the production, optical, electrical, and structural characterization, and behavioral acceptance test on the gas detecting properties of these CO sensors.