A species model for the copper(II)/L‐(+)‐tartaric acid (LH2, tartH2) aqueous system between pH 1.9 and 12.3 has been established by potentiometric, UV/Vis spectroscopic, solubility and crystallographic studies. Eight species were detected, including the oligonuclear major species Cu8L6H–10 in the neutral region and the mononuclear major species CuL2H–4 in the alkaline region, the latter being associated with Fehling's solution. The octanuclear complex was isolated as its lithium salt Li7[Cu8(L‐tartH–2)4(L‐tartH–1)2(H2O)6]NO3·19H2O (1). The “Fehling species” CuL2H–4 was crystallized as its sodium, potassium and caesium salts, namely K2Na4[Cu(L‐tartH–2)2]·12H2O (2), Na6[Cu(L‐tartH–2)2]·9H2O (3), Na6[Cu(L‐tartH–2)2]·14H2O (4), and Cs6[Cu(L‐tartH–2)2]·8H2O (5). Each of them shows a distorted square‐planar environment of copper(II), similar to the related non‐chiral cuprate [Cu(rac‐tartH–2‐κ2O2,O3)2]6– (S. Albrecht, P. Klüfers, Z. Anorg. Allg. Chem.2013, 639, 280–284). By comparing the components of the UV/Vis spectra of Fehling's solution and the solids, we confirmed the identity of the major solution species.