Gas-liquid stratified-wavy POW with low liquid loading is common in natural gas transmission pipelines and offshore gas pipelines. This specific case of two-phase pipe flow has been studied experimentally and theoretically in the present paper. The interfacial behavior during air-kerosene stratified-wavy pow in a 77.9-mm-dia 420-m-long pipeline was observed carefully. The gas-liquid interface usually exhibits a concave downward curved configuration. The liquid film-wetted wall fraction, liquid holdup, and pressure drop were also measured. A mechanistic "double-circle" model and a correlation for interfacial friction factor required as a closure relationship in the model, have been developed. The new model gives significantly improved predictions for both liquid holdup and pressure drop during gas-liquid stratified-wavy pow in horizontal pipelines.