The adsorption of poly(N-isopropylacrylamide) (PNIPAM) at the air-solution interface has been studied as a function of temperature using surface tension measurements and specular neutron reflectivity. At temperatures below 25 degrees C, water is a good solvent for PNIPAM and surface tension measurements show that a saturated layer of polymer is formed at the air-solution interface at very low bulk polymer concentrations. Characterization by neutron reflectivity shows that the adsorbed layer consists of a thin monomer-rich zone followed by a more dilute zone which extends toward the bulk solution up to a thickness proportional to the radius of gyration of the polymer. At temperatures above 25 degrees C, the polymer adsorption increases gradually until around 28 degrees C, beyond which it increases very steeply. This is attributed to a decrease in solvent quality. In the adsorbed layer, the monomer-rich zone also increases steeply beyond 28 degrees C while the central more dilute zone increases only gradually over the entire range of temperature studied. At temperatures above the bulk solution cloud point around 33 degrees C, an inhomogeneous layer is formed which exhibits very slow kinetics to reach equilibrium. We attribute this to a possible "glassy" nature of the adsorbed layer or a possible existence of a surface gel.