In this paper, first, we introduce the new concept of (complex) 2–Hilbert spaces, that is, we define the concept of 2–inner product spaces with a complex valued 2–inner product by using the 2–norm. Next, we prove some theorems on Schwartz’s inequality, the polarization identity, the parallelogram laws and related important properties. Finally, we give some open problems related to 2–Hilbert spa...