Dobson leaves Zenith, where he was European business development director, after 18 months. Prior to Zenith he was vice president of advertising sales at MTV Europe.
Microsoft is sinking $100m (£68m) into the effort globally, with $30m (£20m) earmarked for Europe, the Middle East and Africa.
Dobson will take up responsibility for forging closer ties with advertising agencies in an attempt to attract greater numbers of advertisers to the site. The move is part of an effort to shake-off the lack of confidence in online advertising that has developed partly as a knock-on effect from the advertising slowdown.
In response to the downturn, Microsoft has more than tripled the size of its ad sales team, to 150 from 40 and it has designed a raft of new online ad formats including virtual scratch-off ads, where the ad message can be revealed by moving the mouse over the banner.
These new ads will sit alongside more traditional advertising such as banner, interstitials and superstitials.
Microsoft has developed a new ad-targeting product, which will select the appropriate ads for individuals based on their tastes and preferences, in the same way as DoubleClick's DART system.
Over the past 18 months Microsoft has spent $250m on MSN, which has overtaken Yahoo! as the world's largest internet portal.
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