Can I put 32gb kingston in iMac mid 2010?

Officially, Apple supports 16 GB of RAM, but if you check macsales.com for your model, they support up to 32 GB. Make sure you get the correct RAM for your model - very important.

Please only buy RAM from the recommended RAM vendors here (and Kingston is not one of them): OWC (macsales.com) or Crucial as Macs are very finicky about their RAM. Personally, I will never buy another Kingston product for any of my Macs.

Depends on which size display and the processor that your iMac 2010 model has, 21.5" or 27" Core i3 only support 16GB max, the 27" Core i5 or i7 model can support 32GB max (unofficially).

You can check for individual models detailed specs for yourself here:

http://www.everymac.com/systems/by_year/macs-released-in-2010.html

OWC is a good source to get Mac compatible RAM and can also help you select the right kind over the phone if you need help.

If it is Kigston "Value RAM", return it or just toss it in the

trash as it is typically useless on Macs,