Preheat the oven to 180ºC (350ºF). Grease a bundt cake pan (24 x 8 centimeters (9 ½-inch diameter with 3 ¼-inch-high sides)) with butter and dust with flour.
In an electric mixer, beat on medium speed the sugar, eggs and the orange zest until a homogeneous mixture. Then, pour the orange juice and mix for 1 to 2 minutes until incorporate. Add the flour and the baking powder and beat until obtain a homogeneous and creamy mixture.
Pour the mixture into the prepared pan and bake until a toothpick inserted in the center comes out clean, about 20 minutes (the time depends on the oven).
Remove the cake from the oven and unmold onto a plate. Let cool to room temperature and serve.