Alexander Macdonald was an explorer, author and mining engineer. When he was in his twenties he went to Alaska with Jack London. He was one of the pioneers of the Klondike goldfields and among other adventures led various exploring and geological expeditions in the interior of Australia. He spent some time in Western Australia and Queensland and served with the Australian contingent in the Boer War. He was a Fellow of the Royal Geographical Society. His interest in travelling and prospecting informed much of his writing, his themes derived from living in various frontier regions, including parts of Western Australia and Queensland, and has been indicated by the sub-titles given to his books. Macdonald used a simple style for adventure stories that endorse manly virtues of courage, endurance and mateship, thus directing them frequently to a younger readership.
The tales told In Search of El Dorado : A Wanderer's Experience are autobiographical, described by Admiral Moresby in his Introduction to the book, as 'true stories of gold and gem seeking'. In the Preface to The Lost Explorers, Macdonald wrote that 'I have given a tale of gold-digging and of exploration - a tale, for the most part, of events that have actually happened.' Frequently his characters 'have been with me in my expeditions'.
Macdonald married Wendy, daughter of Dr W. B. Hingston in 1915. The couple had a son and a daughter.