Hi,

Note that baking soda is not the same as baking powder.
Baking Powder is "Backpulver" in German.

Baking Soda is "Speisesoda", 'Backsoda" or "Speisenatron".

It is usually sold under the following brand names: "KaiserNatron" or "Bullrich-Salz

Google and EF Forum search are your friends, don't ignore them

Happy baking

Joey