We are a company based in thika and wish to bring our staff about 30 to visit the national park. Please let us know the charges per pax.

http://www.kws.org/tourism/tariffs.html
The kWS website has last years price of 300 bob for citizens for daily entry to Nairobi.. 1.000/- for residents. Not heard of an increase this year.
Vehicles are extra depending on size.
Edited: 12:29 am, January 10, 2013Hi Eunice, it will depend on which park you are planning to visit. If it is KWS run then the best thing is to check on KWS site
http://www.kws.org/tourism/tariffs.html
Specifically here kws.org/export/sites/kws/tourism/downloads/C…
Also do not forget that a vehicle is also charged based on its passenger capacity, charges are at the bottom of tariff page
Tariffs are for 2012 so you can call KWS and confirm, but I did not see any increase announcement, usually it would be announced.
And note that residents and citizens are charged at different rate
Edited: 12:31 am, January 10, 2013