To obtain useful and reliable pyrolysis data under high pressures, continuous pyrolysis experiments were carried out using a drop tube furnace. To ascertain the reliability of data, a mass balance during pyrolysis was carefully checked. The pyrolysis data obtained in this equipment was compared with previous results, and it was found that the weight loss observed in the drop tube furnace was somewhat larger than those obtained with other apparatuses. The experimental results were compared with those predicted by three pyrolysis models. Although discrepancies between predictions and experimental results were observed under a certain condition, the agreement between the experimental weight losses with three predictions was fairly good at 800 degreesC and 1 MPa with all the models. Product distribution was also reasonably predicted with the Flashchain model. It is desirable to further improve the models by comparing their predictions with more extensive and reliable experimental data.