The clash between Scotland's First Minister Alex Salmond and Better Together leader Alistair Darling was a hot topic in locations as diverse as Stoke-on-Trent in England and Seville in Spain.
Twitter said a total of 255,559 tweets were sent on the debate, with conversation peaking near the end of the cross-examination sections as Mr Salmond questioned Mr Darling on job creation.
The number of tweets per minute also hit a high as Mr Salmond pushed Mr Darling on the so-called bedroom tax, and when Mr Darling quizzed his opponent on his currency plans.
Academics at Aberdeen's Robert Gordon University (RGU) carried out their own analysis of Twitter conversation during the debate using specially developed software.
They created a list of 300 Twitter accounts from Scottish journalists, politicians, bloggers and public bodies interested in the debate.
The team then collected all tweets sent to or from these accounts, as well as all those containing the hashtag #indyref and all tagged as being sent from Scotland.
Professor Sarah Pedersen, who helped analyse the findings, said: "As far as peaks are concerned, interestingly, in comparison to the first debate, we saw the largest surge in tweeting when there was a break in the debate and the video was played.
"This suggests that viewers were highly engaged with the debate and therefore waited for a pause rather than providing a running commentary as in the first debate. There was also a high volume of tweets at the end of the debate, which supports this supposition.
"Again, in comparison to the first debate, where questions from the audience did not attract much attention on Twitter, for this debate we actually saw surges in tweets in response to audience questions, particularly in response to the woman who accused Alistair Darling of being a hypocrite and the question which asked 'If we are better together, why are we not better together already?'
"Of course at this early stage we cannot provide detailed qualitative analysis of the tweets and so cannot say whether these peaks were dominated by positive or negative comments, but anecdotal evidence from trending topics in Twitter suggests that the Twittersphere gave this debate to Salmond."