The ferroelectric properties of MnWO 4 single crystal have been investigated. Despite a relatively low remanent polarization, we show that the sample is ferroelectric. The shape of the ferroelectric loop of MnWO 4 strongly depends on magnetic field and temperature. While its dependence does not directly correlate with the magnetocapacitance effect before the paraelectric transition, the effect of magnetic field on the ferroelectric polarization loop supports magnetoelectric coupling.PACS number͑s͒: 72.55.ϩs, 75.80.ϩq, 75.30.Kz The mutually exclusive nature of magnetism and electric polarization phenomena in most solids 1,2 has recently attracted attention in the scientific community. This is essentially due to both the basic physics challenges posed and the possible magnetoelectric ͑ME͒ applications for memory storage and electric field-controlled magnetic sensors. The idea of having the two order parameters ͑magnetic and electric͒ at the same temperature and magnetically controlled electrical polarization ͑or vice versa͒ has stimulated a vast research of new materials, 3-8 as well as reinvestigation of previously known compounds. 9 It becomes evident that many canted antiferromagnets may develop electric polarization as a result of the overlap of the electronic wave functions and as a result of the spin orbit interaction. 10 Among materials in which magnetoelectric effects have been recently reported, MnWO 4 is a particularly interesting material as the electric polarization in a single crystal may be switched from the b to a direction when a strong magnetic field is applied. 11-14 A similar phenomenon has been observed in rare-earth manganites. 15,16 The antiferromagnetic ͑AF͒ phase transitions of MnWO 4 were already studied a long time ago. 17,18 With decreasing temperature, MnWO 4 undergoes a collinear antiferromagnetic state ͑AF1 phase͒ at T N Ϸ 13.5 K with further transformation to the noncollinear incommensurate antiferromagnetic phase ͑AF2 phase͒ at 12.7 K, and finally to collinear incommensurate antiferromagnetic phase ͑AF3 phase͒ at 7.6 K. Among the three antiferromagnetic states, only the noncollinear one ͑AF2 phase͒ appears to develop an electric polarization that can be explained within the framework of the phenomenological 10,19-21 and microscopic models. 22 Polarity alone, however, does not guarantee ferroelectricity that is sometimes difficult to experimentally demonstrate. 9,23 For example, the reversibility of the electric dipoles could require electric fields larger than the breakdown field, or it might be due to asymmetric irreversible arrangements of the atoms. In this Brief Report, the electric field-induced dipole reversibility ͑ferroelectricity͒ of MnWO 4 is shown, along with the measures of its dependence on magnetic field and temperature. dc ferroelectric measurements were performed in a Physical Property Measurement System ͑PPMS͒ Quantum Design cryostat by using a Keithley 6517A electrometer. The used technique is our adaptation of the already known method, 24 wherein programming te...