Koji Kamoji's reliefs were a successful attempt to depart from the classic easel paintings towards space. This – in both the physical and metaphysical sense – became the most important issue for the artist, leading him to a form of installation that allowed Kamoji to fully express himself. In the Two Poles installation from 1972, he used stone for the first time, referring to the concept of a garden. On each of the four walls of the gallery he hung one big white painting in a pink frame, and placed a large field stone in the centre of the room. Small pebbles appeared in the series of paintings Wanderer from 1980. Koji Kamoji gives a symbolic quality to the stones, in his works they usually mean nature, earth, and reality. In Beginning a Sentence, a work from 1983, pebbles gave importance to existential concepts written on small tablets, such as war, death, or ideograms depicting water and mountains.
Koji Kamoji often uses lines in his works. Sometimes they exist physically in space, for example, such as a metal bar extending from the floor to the ceiling of the gallery in the 1973 installation Flagstone, Metal Rod and the Sky, and sometimes they are only painted in space, like a red line in the 1982 work Site, dedicated to his tragically deceased friend Sasaki.
Koji Kamoji's installations which are built of objects always require a separate room that encloses the work. These works consist in not only watching, but also the possibility of entering them. The aura of the place is also important. Koji Kamoji willingly realises his works in spaces that are not neutral to him, that have a noticeable, specific atmosphere.
In 1986, Koji Kamoji presented a series of paintings entitled The Middle Ages at the Foksal Gallery. It was accompanied by a peculiar manifesto entitled Reflections on the Meaning of Art. The artist compared the Middle Ages with the present day, matching pairs of notions such as prayer and progress, sense and mind, and do not hurry and hurry up.