According to data published by the Electoral Commission between April and June the Tories received the highest number of donations, after it was paid £12.3m by supporters.
Labour, which counts trade union Unite as one of its financial supporters, received £10.8m in donations, while the Liberal Democrats were given £2m.
The rise in donations surpasses 2005 figures of £20.6m, which came just before the election at that time.
Meanwhile, the total amount of outstanding loans between the three largest parties totalled £31.3m by the end of June.
Labour owed the most, with £16.6m in loans. The Tories borrowed £13.1m and the Lib Dems £1.6m.
From 1 March to 30 June this year, the Scottish National Party received £277,000.