A　recent　paper　entitled　＇High　temperature　stability　and　mechanical　quality　factor　of　donor-acceptor　co-doped　BaTiO3　piezoelectrics＇　(Song　et　al.,　Acta　Materialia,　181(2019)　200–206)　reported　a　surprisingly　high　electro-mechanical　quality　coefficient　Qm　∼2010　in　their　BaTiO3-based　Pb-free　piezoelectric　materials.　In　this　commentary　we　show　that　such　high　Qm　value　appears　to　arise　from　a　mistaken　adoption　of　resonance　and　antiresonance　frequencies,　which　is　inconsistent　with　the　IEEE　standard　for　Qm　measurement.　By　using　a　commercial　PZT-8　sample　with　manufacturer-certified　Qm　value　and　electromechanical　coupling　coefficient　kp　value,　we　demonstrate　that　the　calculation　method　used　in　the　above　paper　can　lead　to　an　overestimation　of　Qm　value　by　82　times　and　underestimation　of　kp　to　1/10　of　its　correct　value.　©　2022　Acta　Materialia　Inc.