This paper presents a novel construction of a linear oscillatory synchronous generator designed to be used in a free-piston Stirling engine. High oscillation frequency and short displacement of linear movement present a challenge for the design of the linear oscillatory generator. This work proposes a novel construction of a modular linear synchronous generator. The novel modular linear synchronous generator consists of a basic stationary primary part with concentrated three-phase winding and a basic moving secondary part with permanent magnets. Modular topology of the proposed linear oscillatory synchronous generator enables assembly of different machine lengths according to the required power level by stacking together various numbers of basic primary and secondary modules. Two prototypes of linear oscillatory synchronous generator with different secondary part were developed and tested. This paper presents the electromagnetic design and the results of experimental testing in a laboratory environment. (C) 2019 Elsevier Ltd. All rights reserved.