Abstract: In an ORC (object-oriented real-time computing) environment, it is important to reduce message retransmissions during message passing because these retransmissions cause significant time delay. And, this makes it difficult to achieve the necessary timeliness. A cause of retransmission is message loss due to buffer overflow at the reception side. Here a P+I+D (P for proportional, I for integral and D for derivative) adaptive buffer control algorithm is proposed to prevent such possible overflow. The I control depends on the Convergence Algorithm (CA), which is a stable and efficient IEPM (Internet End-to-End Performance Measurement) tool that predicts the mean message roundtrip time (RTT) of a communication channel quickly and accurately. The P+I+D algorithm was tested under different conditions in a mobile ORC (MORC) environment, where mobile agents collaborate freely over the Internet. The different test results confirm that the proposed P+I+D approach is indeed effective for preventing buffer overflow.