Their pay has also slipped down the rankings to 21st out of 34 countries in the developed world, from 17th the year before.
Unions said the Education At A Glance 2014 report showed that teaching was becoming less competitive than other graduate jobs as a result of the economic crisis and pay freezes.
The maximum salary of £34,000 per year for unpromoted teachers in Scotland is similar in England, but teachers at the top of the scale can earn up to £37,000 north of the border, compared with about £31,000 in England.
Pupil-teacher ratios in Scottish primary schools have also increased in spite of the SNP government’s commitment to cut class sizes, the report found.
In 2007 the SNP promised to reduce class sizes to 18 or fewer in each of the first three years of primary school, but the number of pupils per teacher rose to 21.1 in 2012 from 14.6 the year before.
Scottish secondary teachers spend an average 855 hours in the classroom per year against an international average of 700 hours, which is roughly the level in England. Argentina, Chile, the US and Mexico are the only countries where teachers spend longer in the classroom than Scotland, whereas England is ranked 15th.
Finland, Italy, Norway and New Zealand have all overtaken Scotland in terms of pay, and Luxembourg, Switzerland, Germany, Korea and Belgium give the biggest salaries.
Larry Flanagan, general secretary of the Educational Institute of Scotland, said: “The reality is that there has been gradual erosion of real-terms pay and living standards over the past decade. The problem has been particularly acute over the last few years following the economic crisis and the government’s enforced pay freeze that followed.
“The pay freeze, coupled with subsequent below inflation pay awards both last year and this year, has increased the financial strain on teachers at a time of soaring workload and the huge pressure of delivering a major programme of curricular change.”
Alan McKenzie, acting general secretary of the Scottish Secondary Teachers’ Association, said: “It is not surprising and we have tried to make this clear to councils and the Scottish government, but it has fallen on deaf ears so far with austerity the only answer.
“They need to come to terms with the fact there is sharp erosion in salaries and you will not attract the best graduates to the profession in spite of the popular myth that people are glad to become teachers. The pupil-teacher ratio is variable but government measures have not reduced this as intended and that makes teaching more challenging.”
Andreas Schleicher, OECD director for education and skills, said developed nations were having to decide between smaller class sizes and higher salaries, and many high-performing countries were choosing the latter.