The thermogravimetric analysis (TGA) and electron paramagnetic resonance (EPR) studies of powder and single crystals of bis(acesulfamato)tetraaquazinc(II), Zn(acs) 2 (H 2 O) 4 , a novel coordination compound, are carried out. Previously synthesized bis(acesulfamato) tetraaquamanganese(II), Mn(acs) 2 (H 2 O) 4 , is included into the host in trace amount as a paramagnetic probe for EPR analysis. Single crystal EPR spectra at room temperature are resolved and discussed. Low temperature EPR spectra down to 90K do not show remarkable change. At higher temperatures, however, the TGA and EPR spectra show changes around 335K and 395K; the causes and the mechanisms of changes are discussed.