Is there a reaction to get hydrogen from hydrocarbons?
Hydrocarbons are in fact the main source of hydrogen gas. According to Wikipedia, 95% of all hydrogen is produced by the steam reforming reaction:

$$\ce{CH4(g) + H2O(g) -&gt; 3H2(g) + CO(g)}$$

This is a very important industrial process which has been studied in depth. It is done at very high temperatures (~1000 °C) and under pressure (~20 atm), and can be "up to 75% 
efficient" (though efficiency here may not be defined as solely reaction yield). 

As an aside, the fact that so much hydrogen is obtained from methane (itself generally sourced from natural gas, a fossil fuel) is one reason why hydrogen fuel cells currently have limited environmental benefit, though there is a huge amount of research into more efficient techniques for obtaining hydrogen from water splitting (especially using light) which could be carbon-neutral.