Theo Niermeijer was a sculptor, painter, graphic artist, installation artist, and architect. He was also a contemporary mystic. He received training in Amsterdam, Antwerp, and Warsaw. Theo Niermeijer was a decisive man and an avid traveler.

One of his studios was located in the Zeeburg district of Amsterdam, the polluted area next to the new IJburg. An enormous plot of land with sheds, cars in various states of decay, trucks, and trailers. Hundreds of his sculptures were scattered inside and outside, among wrecks and nettles, leaning against trees and walls.

He was sometimes called 'the iron poet.' Metal was his material: zinc and copper for etchings, stainless steel, and oxidized (sheet) iron to create sculptures. Niermeijer's sculptures are often abstract and made from salvaged materials he found among the remnants near shipyards. Just like his great influence: the American-Japanese-Dutch artist Shinkichi Tajiri. The connection was also thematic, drawing inspiration from Buddhism.

On his yard on Zeeburgereiland near Amsterdam and in the northern French village of Plomion, he assembled scrap iron into three-dimensional sculptures with symbolic and meditative meanings, often with poetic or enigmatic titles that encourage reflection. The impact of time on the material – rust – was a necessary expressive tool for him. He also incorporated metal into his paintings and reliefs. In characteristic 'rust drawings,' the effects of rainwater on metal and paper are evident, similar to the rust on his sculptures.

He traveled extensively, to the U.S., Iceland, North Africa, and the Middle East. These journeys had a significant influence on his work. He was a member of Liga Nieuw Beelden and the Dutch Circle of Sculptors. He also traveled to the Far East, where he was influenced by Chinese and Buddhist philosophy. What he saw and experienced on his travels, he incorporated into his art. Theo was searching for wisdom that pointed the way to enlightenment. 'Zen Buddhism is an invisible hand that stops thinking and helps you create from the infinite sea of creative possibilities. It is absolutely necessary to work a lot, preferably every day, to keep the flow going and to guide your eyes and hands.'