Quorum Sensing (QS), a communication process is prevalent among most bacteria. Acyl Homoserine Lactone (AHL) is the most common QS molecule produced by Pseudomonas aeruginosa and Quorum sensing is believed to be responsible for biofilm formation, pigment production and antibiotic resistance in Pseudomonas aeruginosa. In this study, pigment producing and biofilm forming P.aeruginosa was isolated from air. Autoinducer molecule responsible for quorum sensing was extracted and characterised by HPLC and LC-MS analysis. The isolated autoinducer molecule was analysed for its role in pigment (pyocyanin) production and it was found to enhance the pigment production.