The material properties of several commercial spin‐on glasses were investigated. Infrared spectrophotometry was used to study the annealing effects on the contents of hydroxyl and organic groups. Their concentrations are found to be sensitive to the annealing temperatures and annealing ambients. Both the room‐temperature stress and the in situ stress during annealing were monitored. The measured stress levels of films on Si wafers are low (less than 108 Pa in tensile) compared to other deposited silicon dioxide films. Dielectric properties, including dielectric constants and dissipation factors, were also examined as a function of annealing conditions. A strong correlation between the dielectric properties and the OH content in the film was established. Of the two films studied most extensively, one showed significantly better dielectric properties following low‐temperature (<600°C) curing. Both are good dielectric films for VLSI interlayer dielectric applications if high‐temperature annealings are allowed.