Hey everybody 
Been looking at xiaomi temprature sensors, and see you can get them pretty cheap. I use google home and is intrestet in asking what is the temprature inside. But then can anybody tell me if i need to buy xiaomi gateway to make it work with google home ? Or can i buy only the temprature meters.
The Xiaomi/Aqara temperature sensors communicate via zigbee, which means you need a hub/controller of some sort with a zigbee radio. This can be a SmartThings hub, the Xiaomi gateway, or any number of other zigbee hubs/controllers. Google Home hubs do not have a zigbee radio, so you can’t connect Xiaomi zigbee sensors to it directly.
This forum is dedicated to users of the Samsung SmartThings Home Automation System. If your question is related to the Xiaomi gateway or Google Home and not related to SmartThings, I would recommend looking elsewhere.
Thank you so much, now i got a little smarter 
@Tanja-Marie, If you have a SmartThings hub, you can connect the sensors to it. They are not the best as they were designed to work with the Xiaomi hub, and they tend to drop connection. It might take a few tries to connect them properly.
But once you set them up and they connected, you can share them with your Google Home device and you can query, “what is the temperature in the bathroom”, if your device has been assigned to the bathroom.