In this work, transmission line based metamaterial liquid sensor is proposed to determine the authentic and inauthentic gasoline samples. Proposed structure consists of transmission line integrated metamaterial based resonator layer with a sensing gap. Operating frequency is chosen in X band which is different from the studies in the literature. In addition, this sensor can be used to detect different liquids in X band which can be considered as another advantage of the proposed sensor. In the literature, studies mostly focused on terahertz regime but this study proposes a solution in microwave frequency range. Simulations are carried out by using Finite Integration Technique (FIT) based electromagnetic simulation software. In addition, experimental studies are also carried out to provide accurate results and comparison. According to the results, fabricated structure can be used as a liquid detector. The most important property of the proposed structure is to be compatible to different frequencies between 1GHz and 20 GHz. This metamaterial based sensor can be used in many application fields such as medical, military, oil refineries, and so on. (c) 2018 The Electrochemical Society.