BAUDOUIN de Hainaut, son of BAUDOUIN II Comte de Hainaut & his wife Ida de Louvain (1088-1120, bur Mons). The Chronicon Hanoniense names "primogenitus Balduinus…secundus Arnulphus" as sons of "Balduino comiti Hanoniensi"[252]. The Liber de Restauratione Sancti Martini Tornacensis names "filius eius [=Balduino]"[253]. Otbert Bishop of Liège declared having bought "castellum de Covino" from "comite Balduino de Mont", in the presence of "uxore ipsius Ida, cum filiis suis Baldewino, Arnulpho, Lodewico, Heinrico", by charter dated 14 Jun 1096[254]. He succeeded his father in 1098 as BAUDOUIN III Comte de Hainaut, minor until [1103]. A charter dated 1117 records the donation by "comite Balduino", with the consent of "uxore sua Iola et filio suo Balduino…prefati comites fratres Ernulfus et Willelmus", of "allodium de Oberceiis" to the abbey of Saint-Denis en Broqueroie, signed by "…Gossuinus Avesnensis et frater eius Isembardus…Arnulfus de Crois…"[255]. The Chronicon Hanoniense records that "Balduinus comes Hanoniensis, Balduini comitis et Yde comitisse filius" was buried in the church of Mons[256].
m ([1107]) as her first husband, YOLANDE van Gelre heiress of Dodenweerd, daughter of GERHARD [I] Graf von Wassenberg & his wife --- (-after 1122, bur Mons). The Liber de Restauratione Sancti Martini Tornacensis names "Hiolendem, filiam Gerardi Babinbergensis comitis" as wife Comte Baudouin, in breach of his vow to "Clementia Flandrensis comitissa" to marry "neptem suam" (who later married "Ludovico regi Francorum")[257]. The Chronicle of Alberic de Trois-Fontaines names "Yolendis de Gelra" as mother of "comiti Balduini de Haynaco"[258]. A charter dated 1117 records the donation by "comite Balduino", with the consent of "uxore sua Iola et filio suo Balduino…prefati comites fratres Ernulfus et Willelmus", of "allodium de Oberceiis" to the abbey of Saint-Denis en Broqueroie[259]. She married secondly (after 1120) Godefroi [II] de Ribemont Châtelain de Valenciennes. The Chronicon Hanoniense records that "Yoandis comitissa vidua" married secondly "Godefrido de Bochesin castellano Valencenensi"[260].
Comte Baudouin III & his wife had five children