McTaggart spent four months in 1962 on a working tour through the US, Buenos Aires and England. In 1963 he assembled and presented his papers for an honorary doctorate, which was granted in 1965, during which year he again traveled in Europe and presented in Belgrade at the VIIth International Conference on Phenomena in Ionized Gases, and commenced his monograph on plasma chemistry which he completed the following year.
In April 1967, he was invited by the United States Air Force to the American Chemical Society Conference at Miami, Florida, then addressed the Institution of Mining and Metallurgy Conference in London. In September the English edition of his monograph was published.
On the basis of his work in plasma chemistry, during July and August 1971, McTaggart was sponsored for a tour of the United States by its Office of Naval Research, to be flown by the US Airforce to the NASA-Ames Base to participate in a seminar on plasma chemistry.  In Washington D.C. he presented the inaugural lecture at the IUPAC (International Union of Pure and Applied Chemistry) Conference on Plasma Chemistry, which appointed him a member of its steering committee. Following that, he lectured at the Gordon Research Conference on Plasma Chemistry, held at Beaver Dam.