Plasma medicine has emerged as an interdisciplinary research field combining plasma physics, plasma chemistry, biology, and clinical medicine [8]. Plasma sources, in this field, are mainly focused on plasmas at atmospheric pressure that generate charged particles, radicals, excited species, and reactive oxygen (ROS) and nitrogen species (RNS). When interacting with ambient air, atmospheric-pressure plasma transfers the energy of particles of a noble gas with oxygen and nitrogen in ambient air; consequently, numerous ROS and RNS are generated such as oxygen radicals, nitrogen species, and so on. Here, we also merge ROS and RNS to call them RONS. The cytotoxicity effects of these species contribute to biomedical treatments [9; 10; 11; 12], specifically in cancer therapies [13; 14; 15]. Generally, cold atmospheric plasma (CAP) sources are generated with various electrode configurations [16]. Herein, a dielectric barrier discharge (DBD)-based plasma jet configuration was employed, as it is more adaptable and safer for biomedical treatment. A specific configuration of the DBD-based plasma jet, which is called an extendable plasma jet, was utilized for melanoma cell treatment. Similar configurations were reported for endoscopic plasma applications [17], inner surface modification [18; 19], and bio-targeting of human cell lines, such as A431 (skin carcinoma), HEK 293 (kidney embryonic cells), and A549 cell lines (human lung adenocarcinoma cells) [20]. In the case of biomedical treatment, the use of transferred CAPs, including helium and neon gases, were reported [17; 20]; however, using a transferred CAP including argon gas, has not yet been mentioned for melanoma cancer cells. It should be noted that argon gas was just used for conventional plasma jet systems [20]. It has been found that the temperature of argon plasma with the configuration of the conventional plasma jet rose to around 40 \({}^{\circ}\)C. This heating problem is due to using argon gas [21] that would not be biocompatible. Whereas, using a scheme of transferred plasma, the gas temperature cools when the plasma gas is flowing from upstream to downstream in the jet system. In this case, the gas temperature is kept at a biocompatible level approaching room temperature to avoid harming patients' healthy cells. Furthermore, using the transferred plasma-based configuration, the high-voltage side is kept away to enhance patient safety for future clinical applications. In addition, compared to the large area irradiated with the volume DBD to kill or inactivate melanoma cancer cells [22], the small area of the transferred plasma (with a diameter of around 1-2 mm) are more applicable and allow us to localize the plasma treatment on the skin cancer cells/tumors. RONS are considered to be bioactive products generated by treatment with CAP. Previous findings show that the conventional CAPs offer an approach for treating melanoma skin cancer by RONS induction of cellular apoptosis [22; 23; 24]. Induction of cellular apoptosis by the conventional CAP treatment occurs through the establishment of RONS. The formation of RONS by conventional CAP can also cause damage to DNA and cancer cell death. On the other hand, catalase (CAT) is responsible for neutralizing hydrogen peroxide and for abrogating toxic RONS production [25] possibly by breaking hydrogen peroxide down into water and oxygen. Herein, it is also investigated whether the addition of CAT is able to prevent the toxic effects of RONS, generated by transferred CAP as a developed plasma source. In this study, an argon-based transferred CAP was developed for melanoma skin cancer cells in vitro. First, the transferred CAP with argon gas was characterized electrically and spectroscopically, then it was utilized for melanoma (B16F10) cell and non-malignant (L929) cell treatments individually, as well as melanoma (B16F10) cell treatment with the addition of CAT.