Is possible for two HAM radios to communicate to each other via UHF/VHF without a repeater station?

Yes, it is called simplex operation. Depending on the radio's wattage, terrain and atmospheric conditions, simplex usually can go up to 5 miles or a little more.

FRS and GMRS are UHF radios. Handheld ham radios wouldn't be much different than GMRS 5 watt models. Range is mostly line of sight for handhelds. With a good 5db gain antenna, you're doing well to get 15 miles between 5 watt UHF handhelds, even if you can see each other. The 30 odd mile range you see on some GMRS radios is nonsense.

Several miles depending on which radios and the terrain between the two radios.

But please take the time to get you Ham Radio (Amateur Radio) license and call sign. Find a club near you for assistance. Here is more info...

Ham Radio... It has been around for about 100 year and the new radio gear is so advanced that it will work when the power and the internet is out. 3 million licensed users worldwide. Find a club near you and get involved.

Perfect to communicate to other licensed friends and family day in and day out, and when disasters occur.

Source(s):

http://www.arrl.org/new-to-ham-radio

http://www.arrl.org/find-a-club

http://www.nparc.org/becomeham.htm

You can study on and then take the exam.  Maybe make contact with a club near you so you can find someone to mentor you.  Here is a link to the question pool but buying or borrowing a study book might be better.  There are also free websites that give free practice exams.

If you are talking about hand held radios with rubber duck antennas, apart from perhaps a little more power, FM ham radios are likely to be little better than GMRS point to point (i.e. simplex, no repeater). VHF (144MHZ/2 meters) ham radios will be better than UHF (432MHz/70cm) ones. Single sideband (SSB) portables will have an even better range than FM but to get "serious" you need to use an improved directional antenna with more power and preferably using SSB. I've managed distances of 50 miles or more with 10W of VHF/SSB with a 5 element antenna which is a relatively modest distance for simplex contacts of that type. Further distances can be achieved depending on the equipment at either end and atmospheric conditions. Of course both operators will require the appropriate ham license. It's perfectly practical to use a 10W or more VHF/SSB ham rig with a modest yagi antenna in a portable or mobile (atttached to a vehicle) situation.

Don't transmit with amateur radios until and unless all individual persons

involved in your communications have valid amateur radio licenses

authorizing them to use the band(s) on which you want to operate.

(Listening without a license is legal, at least in the U.S. and most other countries.)

Unlicensed opertaion can easily cause you to be subjected to significant fines.

The FCC likes to throw around numbers like $10,000 -- and they usually win.

Canada and other nations may have similar -- or more severe --

deterrents to unauthorized radio transmissions.

Amateur radio VHF and UHF signals can span much larger distances

than FRS or GMRS.

For a much better idea of the capabilities of amateur radio,

consult a radio manual. Libraries commonly have at least one.

CB radio may be the best choice for many uses, but CB W-Ts

are typically rather large and cumbersome to carry around.

Yes.

Distance will be comparable to similar spec commercial radios.

And yes, of course, each user needs their own amateur radio license, and that is restricted from certain purposes, namely commercial. It depends on your study if it may be illegal.