 <p>For those for whom the solution provided by cpowers and WonderGrub also didn't work, you should check out the following SO question, because for me this question was actually the answer to my occurence of this problem! <a href="http://stackoverflow.com/questions/7204840/rss20feedformatter-ignores-textsyndicationcontent-type-for-syndicationitem-summa">Rss20FeedFormatter Ignores TextSyndicationContent type for SyndicationItem.Summary</a></p> <p>Judging from the positive answer from <code>thelsdj</code> and <code>Andy Rose</code> and then later the 'negative' response from <code>TimLeung</code> and the alternative offered by <code>WonderGrub</code> I would estimate that the fix offered by cpowers stopped working in some later version of ASP.NET or something.</p> <p>In any case the solution in the above SO article (derived from David Whitney's code) solved the problem with unwanted HTML encoding in CDATA blocks in an RSS 2.0 feed for me. I used it in an ASP.NET 4.0 WebForms application.</p>