Experimental data related to 40 MHz Argon plasma parameters in the RF power and pressure ranges of 25-200W and 0.2-0.5 Torr are presented. Electron temperatures are obtained using both double probe and optical spectroscopy methods. Acceptable consistency between results is obtained. Double probe method is also used to obtain the plasma electron density. At any particular pressure value, the effect of increasing RF power seems to be restricted to increasing plasma electron density rather than affecting the plasma electron temperatures. Signature of the Paschen law effect is reflected on the relation between pressure and electron plasma density. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).