|Ireland 69 (27.2 overs) G Dempsey 19, S Kavanagh 15; S Ismail 3-16, S Luus 3-16|
|South Africa 70-1 (16 overs) L Goodall 32*, A Steyn 21*; G Dempsey 1-20|
|South Africa win by nine wickets|
Ireland were bowled out for 69 as South Africa secured a nine-wicket victory in the opening one-day international in Dublin.
After winning the Twenty20 series 2-1, South Africa were untroubled from the off and swiftly dismissed the Irish batters, with Georgina Dempsey high scoring on with 19.
South Africa needed just 16 overs to win having lost just one wicket.
The second ODI between the sides takes place on Tuesday.
Irish captain Gaby Lewis won the toss and elected to bat in her country's first-ever game in the ICC Women's Championship, hoping to put up another strong total to trouble the 2022 Women's Cricket World Cup semi-finalists.
However, Lewis, Player of the Series in the T20Is, was out for a duck and the second and third wickets followed soon after, with the dismissals of Leah Paul and Rachel Delaney leaving Ireland in trouble at 4-3.
Mary Waldron was the next to fall before rain halted play in the 14th over with Ireland at 21-4.
Shauna Kavanagh, playing her 100th international for Ireland, and Sophie MacMahon put together a stand of 21 either side of the delay however their run came to an end with the former was caught on 15.
South Africa captain Sune Luus struck twice to dismiss MacMahon and Sarah Forbes, one of two debutants alongside Arlene Kelly, before Dempsey's high score of 19 gave Ireland a positive in a poor showing at the crease.
Kelly was caught and bowled by Luus, and despite Dempsey's best effort, the dismissals of Jane Maguire and Cara Murray brought Ireland's innings to a close with 69.
That left South Africa needing just 70 to win, and although Dempsey claimed the wicked of Laura Wolvaardt the visitors did not look troubled.
Lara Goodall, top scorer in each of the Proteas' wins in the T20I series, soon got the innings going, striking Kelly and Dempsey each for a boundary in consecutive overs.
The runs began to follow thereafter, with Andrie Steyn combining for an unbeaten, match-winning 55-run stand, Steyn tucking the decisive single in the 16th over.