Can I visit HongKong during 12 hour layover in Guangzhou without a visa?

Hi,
In May I am flying from Amsterdam via Guangzhou to Brisbane Australia. My lay over in Guangzhou is 12 hours. I would like to take the train to HongKong and visit my friend there. Can I do this? Do I Need a visa for China? I am a Dutch citizen and live in Australia.
Thanks!
Astrid