Is there a trick to easily removing stuck rubber hoses off fittings?

Paulster's first option of grabbing with pliers (or your hand, if possible) and twisting is the best I know, but one option for a tool like this pick that's not made of metal is bicycle tire levers:

I have these for bike work, but they come in handy with the car too, any time I need to pry or pick something that might be damaged by a metal screwdriver. Inside trim pieces are one example; there are of course other tools, specifically designed for trim, but these levers have worked well enough for me.

If you also have some lying around, they would be worth a try.

Spray some Windex or wd-40 (if safe) around the end preferably after opening the end with a pliers or your pick or bicycle repair tools.

I bought one of these for my boat, because marine hoses are notoriously hard to remove (seldom done, and often inaccessible). I gave it to a friend, who had to remove original scupper hoses on his 25 year old boat. He told me it worked great. I am now going to order two more.

Agree that petroleum products like WD40 shouldn't be used on rubber hoses. Even a little could cause rubber to disintegrate over time.

Boil kettle. Submerge fitting and hose end in hot water for 60 seconds, it will pull out like a greased pole from a...

If you can't get the fitting submerged, simply pour over the boiled water very slowly for 1-2 mins until the hose is fully heated and softened.

If you can't use water, use a heat gun on low and heat the base of the fitting. In the end the heat will transfer through and soften the hose.

It's the fact the hose is relatively soft that causes it to take the shape of, and grip to the barbs on the fitting. So long as such a hose it warmed up to around 40 degrees, it will become very elastic and far easier to remove.

For very tight and/or steel helix hoses, the tool above or old flat blade screwdriver is still useful initially. But even without, a hot enough hose will yield to a bit of tugging and rotating in the end.

Experience: I build up water displays for events and exhibitions. Often with hundreds such connections. It used to be the bane of my life until I tried using a little heat.

Probably should be a comment, but I'm too long-winded: if the hose (automotive) is really difficult to get off, with corrosion "welding" the rubber to the fitting...

It's time to replace the hose. Once you have the new one in hand, you don't care so much about damaging the old one.

On the other hand I'm the silly cheap type that rinses and dries toilet paper, so I get the dilemma. Careful work with the pick tool pictured can save those rare ellusive hoses that you can't easily replace. All the other [actual] answers are good. I can't say that WD-40 is damaging, but I've used PB blaster on old cruddy hoses for removal and on new hoses to get them well over a series of barbs (older Toyota power steering for instance).

Again I can't be sure, but I feel like a hose that is rated (SAE R or J spec) for fuel, ATF or power steering fluid will not be adversely affected by a bit of PB Blaster or Kroil or WD-40. That's only my opinion. On a "softer" coolant hose, silicone based dielectric grease should have no adverse consequences.

Good play for a 2.5 year-old question. Fully demonstrates what a good question it is.

I was fighting with a stuck rubber hose on my car when it just popped into my head that I had a heat gun in the trunk. I had loaned it out to my brother and he was just returned it to me. It was the kind of gun you would use to scrape paint. I tried it on the hose. I moved it around a lot and just tried to get it to soften the hose up. It worked great. Once you get the hose softer, take a rag to grip it and work it by twisting side to side. Once the connection breaks loose, it’s pretty easy to get off.