In-situ scanning tunneling microscopy (STM) and in-situ alternating gradient field magnetometry (AGFM) are used in combination to characterize the structure and magnetic behavior of Co/Au(111) layers electrodeposited from CoSO4 solutions, with anions X=Cl− and SCN− added in amount traces. In the Cl− solution, the 2-D growth process is briefly recalled. In the thiocyanate (SCN−) solution, preliminary observations show that nanometer clusters accumulate on top of a Co underpotential deposition (UPD) monolayer. Both structures solution/Co/Au(111) exhibit perpendicular magnetic anisotropy (PMA) for a Co thickness t≤t*, with t*∼2 ML in the Cl− solution and ∼4–5 ML in the SCN− one. Results are briefly discussed in light of classical models for PMA in ultrathin films.