import requests
import re
r = requests.session()
page = r.get('http://www.zrsr.sk/zr_ico.aspx')
hidden = dict(re.findall('<input type="hidden" name=".*" id="(.*)" value="(.*)" />', page.text))
hidden['__EVENTTARGET'] = ''
hidden['__EVENTARGUMENT'] = ''
hidden['cmdVyhladat'] = 'Vyhľadať'
hidden['msg1'] = 'IČO musí tvoriť 8 číslic!'
hidden['tico'] = '36379395'
page = r.post('http://www.zrsr.sk/zr_ico.aspx', data=hidden)
print(page.text)