This is an R package that aggregates data from PIAAC 2013. Be warned that the package is about 150 MB.
There are 22 datasets in this package, each with data from single country. Information from the PIAAC website:
The data collection for the Survey of Adult Skills (PIAAC) took place from 1 August 2011 to 31 March 2012 in most participating countries. Around 166 000 adults, representing 724 million adults aged 16 to 65, were surveyed in 24 countries and sub-national regions in the official language/s of the countries
More information about data, coodebook and analysis manual can be found here: http://www.oecd.org/site/piaac/publicdataandanalysis.htm