The constant increase in diversity and quantity of Pharmaceutically Active Compounds (PhACs) detected in waste water treatment plants (WWTPs) effluents is an issue of rising concern due to the potential negative impact of the PhACs on the surrounding environment1. Of PhACs, Ibuprofen, a non-steroidal anti-inflammatory drug, is considered one of the most severe contaminants in the influent of WWTPs, typically being found in the range of 10-400 μg/L. Concentrations of Ibuprofen in the effluent wastewater is considerably lower indicating a partial removal of Ibuprofen2,3. This elimination of ibuprofen is being ascribed to primarily to biodegradation. However, if biodegradation is to be used as a solution for removing ibuprofen from wastewater, figuring out which bacteria are responsible for degrading the compound and understanding the processes by which it is being degraded are the first steps on the way. In the current study, the pathway of degradation of ibuprofen of the ibuprofen degrading strain Patulibacter sp. strain I11 was characterised using quantitative proteomics. The subsequent data analysis revealed several proteins which were up-regulated in response to ibuprofen by Patulibacter sp. strain I11 that might be involved in the degradation of ibuprofen.