Tetraaqua bismaleato iron(II) [Fe(C₄H₃O₄)₂ (H₂O)₄], (1) is a new synthetic antimicrobial agent. Thermal analysis shows that the dehydration of the compound occurs in agreement with the structure. The single crystal salt crystallizes in the triclinic space group 𝑃-1 with 𝑎 = 5.171(2) Å, 𝑏 = 7.309(3) Å, 𝑐 = 9.731(3) Å, 𝛼 = 109.15(2)^°, 𝛽 = 115.02(2)^°, 𝛾 = 92.42(1)^°, 𝑉 = 313.6(3) ų and Z = 1. Three dimensional network is formed by strong intermolecular O – H . . . O hydrogen bonds. Magnetic susceptibility measurements of 1 in the range 2–300 K exhibited paramagnetic behavior at high temperature. However, at low temperature, the susceptibility data showed weak antiferromagnetic interactions between the local spins. Antimicrobial activity of 1 was tested. It showed high response against gram-positive and gram-negative bacteria as well as fungi and the MIC and IC50 values ranged from 8 to 256 𝜇g.mL⁻¹ and from 1.38 to 22.19 𝜇g.mL⁻¹, respectively.