A new 'turn-ON' fluorescent probe, pyrene appended thymine acetamide (PTA), with high sensitivity and selectivity for the detection of uric acid (UA) was developed and first time imaging of uric acid in living cells in water was achieved. 1H NMR and density functional studies on the system have been carried out to determine the nature of the interaction between probe PTA and UA. © The Royal Society of Chemistry 2016.