In situ gel drug delivery systems are in solution form before administration but once administered, undergo gelation in situ, to form a gel. In the present study nasal in situ gel of Phenylephrine hydrochloride was prepared for the treatment of nasal infections to provide sustained release of drug and to attain site specific action. Carbopol 934 was used as a pH triggered polymer and Poloxamer 188 was used as thermo sensitive agent. Different formulations were prepared by varying the concentrations of Carbopol 934 and Poloxamer 188 polymers in combination with Hydroxylpropyl Methylcellulose (HPMC), HPMC E5LV, HPMC E15LV, and HPMC E50 LV as viscosity enhancing agents. These formulations were evaluated for parameters like drug excipient compatibility, pH, drug content, gelation temperature, viscosity, in vitro drug release, mucoadhesion, ex vivo permeation and stability studies. FTIR study revealed that there was no interaction between drug and polymer. pH of all the formulations were found to be in the range of 5.4-6.2 and the drug content for all the prepared formulations was found to be in the range of 94%-99%. The results of in vitro drug release and mucoadhesive strength indicated that the optimized formulation F15 and F18 is the most successful formulations of the study, exhibited a sustained drug release of in 77.8% in 6 hours and 70.8% in 8 hours with a mucoadhesive strength of 3124.64 and 3167.76 dyne/cm2. From the results it is concluded that Phenylephrine hydrochloride nasal in situ gel produces prolonged and site specific drug delivery for the treatment of respiratory tract infections especially for sinusitis and bronchitis.