Preheat your oven to 350°F (175°C). Grease and flour a bundt pan.
In a large bowl, whisk together the flour, cocoa powder, baking powder, baking soda, and salt.
In another bowl, combine the sugar, buttermilk, oil, vanilla extract, and eggs. Mix well.
Gradually add the wet ingredients to the dry ingredients, mixing until just combined.
Slowly add the hot water to the batter, mixing until smooth.
Pour the batter into the prepared bundt pan.
Bake for 50 minutes, or until a toothpick inserted into the center comes out clean.
Let the cake cool in the pan for 10 minutes, then turn it out onto a wire rack to cool completely.