Which technology is more demanding in web development out of these two Adobe Flex and HTML5?

We can't compare both of them because both of them have their importance and have advantages and disadvantages.

But answer to you question:

I believe HTML5 is more demanding than Flex nowadays.

Dear Mohammad,

You are comparing a program to an actuall programing language which is HTML5.

And i personally, vote for the seond one.

Big question. Adobe Flex is an SDK (Software Development Kit) that includes a User Interface Framework, a command line compiler and other tools. The output of an Adobe Flex application is either a SWF, which runs in the browser based Flash Player, or an AIR file which will run in conjunction with Adobe's desktop runtime.

HTML5 is a spec for the next version of HTML. HTML is a markup language for building web pages. It includes some new aspects for dealing with video (Video Tag) and for creating animations (Canvas).

HTML5, alone, is not a good choice for building Applications.

Html5 main reason is its free oen sounce unlike flex and vgood from beginers to expert and flexible then flex

If we go in comparison then defintiely HTML5 is better then flex. Because major work is done when upgraded to HTML5 and demand of it goes tremendously high after that.

Also i haven't seen any significant changes in flex in near past.

Always  we have improvment in technologies , before having html5 technology , we used to use adobe flash , or flex and we were satisfied with it ... untill the booming of Html5  ... so of course html5 is more demanded 

Offcourse HTML5, Why someone want to stuck with a framework and want to learn a new thing when with some addiiional libraries or custom code you can achive same within native language 

both technologies have their own importance, advantages and disadvantages but in my opinion 

flex is better then html5 cuz html5 is not mature yet.

The Answer for this is very simple as the HTML is native to the browser while Flash/Silverlight etc. are not native to the browser, so you will always required to download seaprate plugin in order to run any application under that.

On the other side, currently JQUERY (this is based on JavaScript only) is driving the web market as if you see that is cross browser and high performance. there are so many plugins available which gives very high interactive ness ease of developers life. e.g. Kendo UI, Angular JS etc.

So, I would like to suggest to use HTML+JQUERY for the web development now days as these are client side, interactive, easy to use, work cross browser, no plugin required to download .....

Thanks

of course HTML5